Hi 😊. Just joined today. Have a 22'x54" Coleman still in the box. Trying to get ground and 12"x12" concrete footers level. Read all of the posts on foam board bottoms last year. Sounds like a good plan to me. But I think I bought the wrong boards. I have 3/4" x 20 1/2" x 8' white styrofoam boards. Before I go to all the trouble of taping them together please let me know if I need to get different boards. Thank you!