My Argosy Minuet has the aluminum subfloor. It is sagging between the floor joist - which are 4' apart. As a home builder, where floor joist are placed every 16", it amazes me that no one has fallen through.
I'm renovation mine now, and plan to put 5/8" plywood down, after I have sealed it with polyurethane and then "float" a flooring material on top of that. This involves rolling out a thin roll of rubber padding and then installing interlocking vinyl planks together. This flooring is relatively new, extremely durable, water resistant and easy to maintain and change out any pieces that get damaged in use.
Good luck in your remodel!
You could use this roll of padding (Home Depot) on the aluminum subfloor to cushion and warm the flooring.