Screws for securing items to motorhome floor

Hi there,

I posted this almost two years ago, and now I'm finally ready to hit the road.

I purchased a well-maintained 2001 Newmar Mountain Aire 3763 on the Spartan chassis. I'm picking it up this Saturday and the first thing I need to do is add a desk to serve as my mobile office. I want to buy something like this:



And secure it to the floor using metal brackets.

My question is - what's under the flooring? Plywood? Can I just use wood screws to secure the desk?

Thanks in advance!