Looks like you and I are running identical setups - or we will be once I add a false bottom
Looking at the MoreBeer website they show the handle in the center. I'll call them when they open to ask as this would potentially affect things for me.
From your sketchup pic it looked like 4"-4.5" was easily doable, but from those pics it looks like 3.75" would be the max with .25" of clearance?
How tall is the handle on the false bottom? I was going to suggest doing a shorter screen to clear the handle by say 1/2" to get the wider screen until I started looking at the dimensions as I'm less worried about total volume as I am surface area:
Your current design:
14.5" Wide X 12" Deep = 174 sq inches
I'm guessing at what additional width we could get by going to 4.5" deep and what the handle height is:
15.5" Wide X 10.5" Deep = 162.75 sq inches
15.5" Wide X 11" Deep = 170.5 sq inches
So that could actually be taking a step back with the shorter ones even with the additional width.
The other consideration is that I mostly do 5.5 gal batches - so much of the screen won't even be used so that clearance at the bottom is a big deal. In this kettle 1 gal uses .95" in height so 2.5" equals about 2.4 gals. Today my bags tend to float but they do eventually sink somewhat. So raisingthe height would lessen the exposeure space even more. Maybe I'm over thinking this part but I'm thinking maybe not using the false bottom at all then...or getting a domed false bottom and a pickup tube? Or just sticking to your planned height of at least 12"
Lastly, I think for the lid to fit reasonably well we would also want a 1/2" drop so 11.5" height: 14.5" Wide X 11.5" Deep = 166.75 sq inches (a 4W X 11.5D cylinder would have 144.44 sq inches of surface area).