The real way to do it is remove the stall and epoxy patch it from the bottom. The stress on the floor is in tension on the bottom outside so that is where the repair needs to be.
That or as mentioned above a new liner installed over the current stall. Problem there is going to be the drain connection. Hard to get to under there.
WBCCI 12156 AIR 3144 WACHUNG TAC NJ6
2004 Excursion 4x4
1991 34 ft. Excella +220,000 miles, new laminated flooring, new upholstery, new 3200 lbs axles