Beverly, It may help if you post some photos of your bench area so people can give you better input. Is your bench all
fiberglass across the entire base, or is there an opening in the middle? My gf's boler had a gap (for porta potti_storage) in the center, so it was just a matter of removing the plywood insert that spanned across this opening under the cushions. Then she just installed the table and seat cushions.
I have a
UHaul and was able to do the same thing. I've posted photos of mine. The first photo shows the original bench with folded down bunk (back cushion). You can see the opening under the cushion. I took off the bunk, and then made the dinette in that opening.