Teardrops n Tiny Travel Trailers

I'm curious on opinions about the plywood floor in a cargo trailer.
I am debating how to go about my build.
Should I:
• Remove the ¾ " plywood flooring and seal it with a good primer/sealer ( I was thinking about something like this) https://www.homedepot.com/p/Zinsser-Bul ... /100398391 - then just reinstall this original plywood. Or;
• Remove factory plywood and use "Advantech" subflooring https://www.huberwood.com/advantech/pro ... h-flooring - without any primer/sealer. (I believe this product cannot be painted). This is what the ATC trailer company uses in their trailer floor by the way… Or;
• Install much more expensive "marine grade" plywood (and seal it with something like the product in the first bullet above)
Fyi- I will be insulating the floor from below; with 3" closed cell spray foam- hopefully this in itself will create a water barrier from the bottom side. I am more worried about water getting into the plywood from the top, the edges and through fastener holes.

Thanks in advance for any input!

I used the exisitng 3/4" plywood that came with my CTC. It was sealed from the factory (not very well however), but I put in 2" foam insulation with foil backing underneath which effectively keeps all the water and etc. off .

If the concern is rotting and you plan to insulate anyhow... that should take care of the concern IMHO.

Foam can just trap moisture, delay its drying out, don't rely on that alone for vapor barrier

If long life is desired, full sealing is key, especially thick for the edges, treat it like a boat deck, bedding any subsequent penetrations.

The installed floor with triple-good full encapsulation should do it if you don't want to spring for the good stuff.

Ok, thanks for the information