Have an old aquapro leaks everywhere
Have seen rescue ribs filled with foam
Has anyone done this?
What type of foam?

The foam will eventually absorb water and be very very heavy. I think the next failure point of your aquapro will be the transom falling off. Thats what happened to ours anyway. But for $250 and 5yrs it was kinda good but an awful shame its a throwaway job though.