Converting All-Grain Oktoberfest/Marzen to Partial Mash

[Starbug]

I'd like to have an Oktoberfest ready for Oktoberfest or at least by October if possible though I'm starting to think I should have started sooner for lagering purposes as brew day would be around 2nd week in Aug.

That aside, my issue is I've got a partial mash setup, using grain bags, and I don't have the capacity to easily and cleanly do the full amount of vienna in the recipe. The Munich, of course, can be easily substituted with LME or DME but what can I do to keep the abv nearish to where it should be and still keep it tasting like and characteristic of a 'proper' Oktoberfest/Marzen with my current set up?

I would be really wary of using more than 7-7.5 LBS of grain with the bag and strainer I'm using.

This is the recipe I'd found, I'm not well versed in this style so I'm very open and appreciative of any insights, changes, substitutions, etc.


Recipe Type: All Grain
Yeast: Oktoberfest/Marzen (planning on using Wyeast 2633 as I'm reading the White Labs oktoberfest takes longer to ferment)
Yeast Starter: Yes- large
Batch Size (Gallons): 5
Original Gravity: 1.054
Final Gravity: 1.014
IBU: 26
Boiling Time (Minutes): 60
Color: 12
Primary Fermentation (# of Days & Temp): 10 at 50 degrees
Additional Fermentation: lagering
Secondary Fermentation (# of Days & Temp): 14 at 55 degrees

8 Pounds Vienna Malt
1 pound munich malt
8 oz crystal 80L
8 oz caramunich malt
1 oz Tettnang (40 minutes)
1 oz Hallertau (30 minutes)

Beta rest at 140 degrees for 30 minutes. Alpha rest at 158 degrees for 30 minutes. Cool wort to 50 degrees and pitch huge starter. Primary until 75% done, then taste for diacetyl. If needed, do a diacetyl rest. If not needed, rack to secondary for 14 days then begin to drop temp gradually until at 35 degrees. Lager for six weeks. Bottle, allow to carb at room temperature and then store at cellar temps.



My current plan was to sub in 3lbs of munich LME or DME for 1lb munich and 2lbs of the vienna, though i'm toying with the idea of replacing a pound or so of the vienna for german pilsen. Since I'm not doing all grain, I'm considering going with something closer to the recipe's I'm used to with a 45min steep at 155 degrees.

Also I thought hops in this style were primarily used in bittering, why a 60 min boil for a 40 and 30 min addition? Should I decrease boil time or bump the hop additions out to 60 and 45-50?


Thank you for your time, any comments would be greatly appreciated.

 

[Starbug]

I read up a bit more, listened so a podcast about it and pretty much totally rebuilt it.

I went for a 90 minute boil, decreased the mash temp to 146 degrees, increased the boil size to 4 gallons, added some Tettnang (though I'm wondering if I should stick with the saaz and hallertau) and decided to try the whirlfloc tablets because I've heard good things.

Brew Method: Partial Mash
Style Name: Oktoberfest/Märzen
Boil Time: 90 min
Batch Size: 5.5 gallons (fermentor volume)
Boil Size: 4 gallons
Efficiency: 75% (brew house)

STATS:
Original Gravity: 1.059
Final Gravity: 1.015
ABV (standard): 5.82%
IBU (tinseth): 22.54
SRM (morey): 9.61

FERMENTABLES:
3.5 lb - Liquid Malt Extract - Pilsen (32.4%)
3 lb - American - Vienna (27.7%)
1 lb - American - Pale 2-Row (9.2%)
1 lb - Belgian - CaraMunich (9.2%)
1 lb - Liquid Malt Extract - Munich (9.2%)
1 lb - United Kingdom - Maris Otter Pale (9.2%)
0.3125 lb - American - Carapils (Dextrine Malt) (2.9%)

HOPS:
0.75 oz - Domestic Hallertau for 90 min, Type: Leaf/Whole, Use: Boil (AA 3.9, IBU: 7.42)
0.5 oz - Tettnanger for 75 min, Type: Pellet, Use: Boil (AA 4.5, IBU: 6.14)
0.25 oz - Saaz for 60 min, Type: Leaf/Whole, Use: Boil (AA 3.5, IBU: 2.08)
0.25 oz - Domestic Hallertau for 45 min, Type: Leaf/Whole, Use: Boil (AA 3.9, IBU: 2.12)
0.75 oz - Saaz for 30 min, Type: Leaf/Whole, Use: Boil (AA 3.5, IBU: 4.79)

MASH STEPS:
1) Infusion, Temp: 146 F, Time: 45 min, Amount: 3 qt

OTHER INGREDIENTS:
2 each - Fermcap-S, 1 drop each, Time: 61 min, Type: Other, Use: Boil
1 each - Whirlfloc Tablet, Time: 15 min, Type: Fining, Use: Boil

YEAST:
Wyeast - Octoberfest Lager Blend 2633


I'm still fairly unsure of it, any advice?