Boil size and when to add LME (Blue Moon clone)

I'm planning on a partial mash of a Blue Moon clone of sorts. I have 3.3lbs. LME to use up from extract days.

I'm mashing the wheat, 4.5lbs, which should call for 1.4G of water. Since I'm using LME for the rest of the grain bill and I'd prefer to add it later in the boil for clarity...should I NOT boil the full 6+ gallons right after sparging the wheat?

I was thinking maybe I'd sparge with 3g. and when I add the LME at 20m, I'd add the rest of the water (boiling) to get me just a touch above final volume.

The hop addition is at 60m (recipe here), so I know a smaller boil volume will lower the IBU's a bit. Perhaps I should up to 1.5oz.

Any other problem with doing the boil this way, adding more boiling water later in the boil to reach final volume?

I believe if you add only a portion of the water but all of the extract, the beer will become darker sooner and carmalize a bit more than if you had all the water. Similar to a gravy that's getting thicker and thicker. BYO had a good article mid 2011 I believe on extract. Helpful hint is to add half of your extract at the start and then the other half about 15 minutes left in the boil. It will help minimize carmalization.

I ended up botching half the process (first BIAB partial mash) due to the flaked wheat I was dealing with. Note to self (and anyone else): Don't use flaked wheat or oats in a bag-based mash system. The gelatinous liquid that results won't flow thru the bag.

I added the LME with 20 minutes remaining. My LHBS guy (www.kirksbrew.com) said full boil then LME later was fine and would give me better hop efficiency. He also mentioned not to use too much sparge water trying to get to the pre-boil volume. You can add water prior to boiling, but after sparging.