[tsubaki]

I've always been told horror stories of saturated foam in a boat.
Had the pleasure of gutting one a few years ago, we went to the extreme to keep a count of the amount of water. This boat actually had 6" of water above the floor, idiot left the plug in all winter.
After all was initially drained, keeping a cut off barrel beneath the drain hole for a few weeks, checking daily, then later removing the floor, we could account for less than 5 gallons of water that was either trapped and/or absorbed by the foam.
We were convinced saturated foam was the problem, found out it was just a heavy boat.
I'd be more inclined to think the slight imbalance of weight is the culprit more than the wet foam.
I've got saddle tanks, everything is perfectly balanced except when I burn about 10 gallons of fuel from one tank. Causes the same situation you are describing.