I have worked with aluminum sheet and plate for the past 30 years, the last 20 in a marine environment.
for a boat, you want 5000 series aluminum. 5052 is softer, however forms easy. 5083 is stronger, however doesnt form easy
1/16" aluminum will dent if you pick it up wrong
1/8" aluminum will dent with your thumb
3/16" will be OK if your structure grid will support it properly. we use no more than 12" centers on the support tubes.
1/4" will span about 24"
they all will eventually dent in the area where you stand unless you have a good structural foam underneath.
there is a reason that its not used.
if you are determined to do an aluminum floor. look at the aluminum decking from T&C or Eastern Metals.
https://www.tc-alum.com/products/industrial/decks-docks-seawall/ works OK for van bodies, work platforms, docks, decks, etc.
