I had an old escort van which the back was fully fibreglassed the sides and the floor i loved it any spillages i would squeegee it out with an old squeegee leave the back doors open and it would be dry in 10 minutes.Then i took it for an mot and it needed welding on the back end they gave me a price for the welding, but when they opened
the back doors and seen the fibreglass floor added on another couple of hundred to remove and refit fibreglass floor as they said it would be a fire hazard when welding. So if i used fibreglass again i would put the fibreglass onto plywood and screw it to the floor then seal around the edges silicon. That way you can remove it yourself in no time.