I think you can pretty much ignore the contribution of hops to the SG, 1 IBU is (roughly) 1 mg of Iso-Alpha/Litre of beer so 100 IBU would be 100/1000 or 0.1g/L, contributing 0.01oP to the gravity or 0.00004 to the gravity, if the other hop products that went into solution were 100 time as massive as the bitterness you might just notice them on an hydrometer (maybe).
If you look at a grain COA you will often see saccrification time in the 10-20 minute range this is the time it takes the enzymes to make the starch soluble, its far from the time required to reduce the starches to the right ratio of fermentable sugars and dextrins that we want for beer to taste good.
Were I fermenting this beer, I would be very tempted to take a small sample and ferment it warm (25oC+) and see where it is going to finish, if the terminal gravity is ridiculously high I would seriously consider adding some dry enzyme which will tackle soluble dextrins and reduce them to fermentable sugars.
Anyone who squeezes a BIAB bag gets what they deserve, a bunch of extra protein into the kettle, to no net gain. There are lots of high molecular weight proteins (n=40K+) that condense (form break) at mashing temperatures. In a conventional system these are trapped in the grain bed, the higher the weight of a protein the more harm it can do to the finished beer, squeeze the bag and you can get them out, allow the bag to drain naturally and few if any are going to find their way into the kettle giving you a lot less trub to manage.