I agree. I have a 1" thick cracked hockey puck of epoxy. A 2" thick (only cracked on top) of 2k regular build. And a whole cup (32 oz.) of Evercoat G2 but it did not crack. And a 3/4" thick puck of universal clear. I just saved them to see what they would do. Except for the G2, that was my fault by adding too much activator while talking on the phone. LOL.
I'd epoxy the bottom, seam seal it, and shoot topcoat on top. Thats how I did my floor pans. I used black epoxy on the bottom and grey inside the car.