I stuff my float bags in the ends empty, with no air in them at all, they fairly easily are then poked up to the ends. Just need long inflation tubes so they can be blown up inside the boat. Still in designs with long skinny ends that are hard to get float bags into they also don't have a lot of volume up in those ends so you're not losing all that much flotation if the bags can't be up there.

Downside to foam for flotation is that unlike air the foam does weigh something and that weight means it'll float a bit less per cubic area. Rare to find foams that weigh less than about 2.5 lbs. per cubic foot, plus whatever weight they gain with moisture absorption so that weight comes off what they'll float. Generally water weighs about 60 lbs. per cubic foot (sea water a bit more) so you can figure out how much flotation you'll gain using the foam.

Bill H.