I need to re-read your post but
This is my fuel deck … mind you in a 23
I thought my deck was fine too....
This is what I found after I took it out!!!
As for foam … in general it is ill advised to foam in the tank (I’m not sure if that’s how you plan to redo it). That moisture you talk about is the moisture that will, over time, destroy the tank. Unless the fuel cell is totally sealed foam can create problems.
I would thoroughly, methodically, painstakingly check that deck out before you drop a new tank in there