You have been given some great advice about tweeking your recipe more to the guidelines of an American Pale Ale (more in line with EdWort's recipe or a SNPA clone), but if I understood you right, you are looking to take things a step further and make a West Coast Pale Ale, which I think is more accurately called a baby IPA (all the hops, 1/2 the alcohol).
The Maltose Falcons have their own style guide that you might find helpful. I'll cut and paste their guidelines for American Pale Ale and West Coast Pale Ale so you can see the differences.
CLASS 5. AMERICAN-STYLE PALE ALE
5.1 American-Style Pale Ale
Aroma: Usually moderate to strong hop aroma from dryhopping or late kettle additions of American hop
varieties. Citrusy hop aroma very common. Esters vary from low to high. Diacetyl moderate to none.
Appearance: Pale golden to amber. Flavor Often moderate to high hop flavor. Citrusy hop flavor very common (such as from Cascades), but also other American hop variety flavors are found. Malt flavor moderate relative to aggressive hop flavor and bitterness. Balance towards bitterness. Caramel flavor is usually restrained. Diacetyl moderate to none.
Mouthfeel: Many are rather light, refreshing and more highly carbonated than other styles, but body can reach medium. Carbonation borders on effervescent in some examples.
Overall Impression: An American adaptation of English Pale Ale.
Comments: American Pale Ales differ from American Amber Ales not only by being lighter in color, but also in having less caramel flavor and usually being balanced more towards hop bitterness. American Pale Ales are often lighter in color than English ones.
History: An American adaptation of English Pale Ale.
Ingredients: Pale Ale malt, typically American 2-row. Light to medium crystal malts. American hops, often the citrusy ones such as Cascade, Centennial and Columbus, but others may also be used (e.g. Brewer's Gold or Willamette). Water can vary in sulfate content, but is often lower than in English versions and the carbonate content should be relatively low.
Vital Statistics: OG: 1.045 - 1.056, FG: 1.010 - 1.015, ABV: 4.5 - 5.7%, IBU: 20 - 40, SRM: 4 - 11.
Commercial Examples: Sierra Nevada Pale Ale. Mad River Steelhead Extra Pale Ale.
CLASS 10. AMERICAN WEST COAST-STYLE BEERS
10.1 West Coast Extra Pale Ale
Aroma: Usually moderate to strong hop aroma from dryhopping or late kettle additions of American hop
varieties. Citrusy hop aroma very common. Esters vary from low to high. Diacetyl moderate to none. Malt aromas tend to be low in relation to the hops.
Appearance: Pale gold to light amber. Head is generally bright white and crispy. Clarity may suffer from a slight hop haze.
Flavor: Flavor is dominated by hop bitterness and flavor with just enough malt to temper the aggressive hop character. Diacetyl is moderate to none.
Mouthfeel: Body is light and brisk with a sharp bracing hop character throughout the palate.
Overall Impression: A brisk, hoppier version of the American Pale Ale.
Comments: This beer presents a similar hop profile to a pale ale or IPA, but with a lighter malt profile to showcase American hops.
History: An offshoot of the American West Coast craft-brewing trend to aggressively hopped beers. This style fills a gap as highly hopped beer that remains low in alcohol.
Ingredients: 2 Row Pale Malt, Light Crystal Malt, American Hops with a tendency towards the citrus character of Cascade, Centennial or Crystal.
Vital Statistics: OG 1.040-1.055, FG 1.008-1.015, ABV 3.5%-5.5%, IBU 35-55, SRM 4-8 .
Commercial Examples: Alesmith X, Mad River Steelhead Xtra Pale Ale, BJs West Coast Xtra Pale, Green Flash Extra Pale Ale, SLO Brewing Extra Pale Ale, Three Floyds Extra Pale Ale
The most important thing to extract from the WCPA is "Comments: This beer presents a similar hop profile to a pale ale or IPA, but with a lighter malt profile to showcase American hops."
So I actually think you should stick with the lighter crystal or carapils instead of switching it to the 40L. Firestone Walker makes their Mission St Pale Ale without any true "crystal".
(via EricCSU)
OG 1044
IBUs 12.2
SRM 4.1
3.85kg Pale Malt 80%
720g Munich 15%
240g Carapils 5%
90 minute boil
7g Fuggles 4.75%AA at 90m
7g Chinook 13%AA at 30m
24g Cascade 6% at 0m
24g Centennial 10.5%AA at 0m
24g Centennial dry hop
24g Cascade dry hop
WLP002
Mash at 145F for 60m, 155F for 10m, then mash out
RO Water, gypsum and CaCl to 100ppm
Cool to 17C and pitch, raise to 19C after 24 hours.
Discussion Notes:
IBU is calculated lower due to the 45 minute whirlpool which provides not IBUs according to Rager. However, Chad did not use a long whirlpool, so he changed the hops to Chinook at 60m and Cascade/Centennial at 30m. Chad dry hopped at 5 days in primary and cold crashed at 10 days, kegged at 15 days. He did not that the sample he tasted after crashing did not taste right, but after carbing, that off-flavor went away.
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In your case, you would be omitting the Munich because it can't be steeped (but can be substituted with Munich extract). That would leave just carapils. I think you would be happy with this recipe, because it is not really a beer that should be defined as balance; it is supposed to have a malt bill that does not interfere with the hops you are trying to showcase. The only suggestion I would make is to reconsider the Simcoe as your bittering addition. I think you are better off in this recipe with a clean (like Magnum) or complimentary (like Columbus) bittering or boil addition because the Simcoe's "dankness" may interfere with the citrus from the cascade.
In summary, keep the malt light and simple, aiming for a lower end OG. Choose a utility hop with clean bittering, and drop a citrus bomb at the tail end of the boil. Additions anywhere in the 10/5/0/hot whirlpool will not be mistakes. I also don't think you could be too aggressive with a dry hop. I think 1 oz is a minimum, not a maximum. The hop schedule for the Epic Pale Ale recipe may also be worth looking at. It is another tweener, too hoppy for a traditional American Pale ale, not enough alcohol for an American IPA. His recipe is a little more malt forward than the Mission St, but he crushes with Cascade hops. Here it is.
7g Cascade 7.5%AA at 75m
14g Cascade at 30m
34g Cascade at 10m
42.5g Cascade at 0m
Wait ten minutes
42.5g Cascade - hot whirlpool for 10 more minutes
57g Cascade dry hop dose 1 at ferment temps for 5 days
57g Cascade dry hop dose 2 at cold crash temps for 5 days
Joe