[A/S] Overlander Toilet question

[SHMossLanding@xxxxxxx]

Our 1965 Overlander has the rear bath.  It has the cover that folds down over 
the toilet seat.   For some reason the porcelin toilet bowl is about 1/2" 
below the fiberglass that holds the seat.  When previous owner  installed the 
seat, he tightened it down and of course, because of the 1/2" gap, it pulled 
through the fiberglass. My question is, are all the bowls like that, or are 
they supposed to be uptight against the fiberglass?  Should I put plywood 
under the fiberglass to support it, or is it designed to float free to 
relieve stress when traveling?

                                     Thanks,
                               Chuck & Lynn
                               1965 Overlander