this was my response to a PM on another forum:
My DIY cost ~$500 and ~50 hours labor. As a Alabamian, I am very pleased with my floor, after all that work, having it turn out better than planned is a real treat. As you know, sometimes DIY projects don't work out so well....
Anyway, I installed Armstrong 12-in x 12-in Crescendo Marble Gray Marble Finish Luxury Vinyl Tile from Lowes. About a $ a square foot. The hotter the weather, the better it forms to the sub floor contours and once stuck down and rolled (or just walked on a lot), IT AIN'T COMING UP. Really! I've also installed 3 other versions of these in my in-laws house (upstairs in their 75 degree heat and downstairs on the concrete basement floor. They all look great, especially when grouted. Then they are hard to tell from real ceramic tiles.
No worries about high temps or humidity at all.
Going on two years and no sign of any wear, shinkage, staining, fading etc. It must get up to 100 degrees in the camper during summer storage.
Good luck on your project. You may need to add a layer of thin plywood if your chassis bolt heads stick up. I glued and shot mine. Also, I used a liquid product Lowes recommends on the plywood to help the tile stick. Its basically just a watery coating that dries quickly to make the subfloor non-porous to improve tile adhesion. It works well too.
The stuff is heavy and we all noticed a real decrease in road noise with this sheet of tile down.