I'll second Snow's opinion.
You can even use fiberglass matting and rosin to patch the floors up because it does have a 'frame' under there for stiffness. I have used duct tape, the real metal stuff and the soft stuff, to cover the gaping holes, then applied the glass mat over top and had that repair pass vehicle safety inspections on 'many' different vehicles with no comments other than a real hard thump on the area by the inspector to make sure it was a 'solid' repair.
Our 88 currently has plywood for the drivers side floor. I am going to retire it though and maybe put my 87 that still has floors on the road if the city will give me enough time to swap the parts. Both need full clutch systems though... :-( (got a new apartment building up across the street and they 'really, really' don't like my rust bucket driveway beaters. The complaints are flying fast and furious. I am thinking on painting the one fingered salute on my garage door...
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06