I used something like that for the bottom of the floor, after I covered it in fiberglass cloth and epoxy, but for the top I wouldn't use it. It has rubber crumbs in it and would be hard to keep clean. The Monstaliner does not have any rubber crumbs in it and it is a two part paint which is much more durable. If you are trying to keep cost down then several have used the mix or CPES or epoxy to seal from water and painted with roller using several coats Rustoleum or one part boat paint. Sanding in between coats to make it smooth if desired.
Cheapest option is seal for water protection and paint with house paint. No one best way, all depends on skills, personal preference, desired looks, money, and desired longevity. Checkout all of the builds in the Hall of fame and you will get a sense of what will work for you.
I stayed away from Aluminum due to the vast amounts of hail we get in Colorado, so my chosen method gave me the look I wanted with the long planned life, but wasn't cheap. The Monstaliner is easy to power wash after a camping trip, doesn't chip (worked so good I skipped the diamond plate I had planned on front and around the bottom edges, also saved some weight) and it can be easily waxed as it is a light orange peel type texture.
Dan