What is the layup on the inside, because it obviously was not enough across the bottom of the boat? Unfortunately, strippers don't tolerate bottom bounce very well. You could try bending ribs into it, but the job would be a pain and you're also creating a potential maintenance problem and probably adding an awful lot of excess weight. A better, stronger, more durable and lighter bet for ribs would be glassed-over half ribs across the bottom, spaced every 12"-18" or so. These could have a cross section that is maybe 1" wide at the base, rounded on top and about 3/4" tall. You could use balsa (you can even buy pieces designed and pre-shaped for the leading edges of model airplane wings at hobby stores) but cedar would probably be better and isn't hard to shape. It's almost as light and does not soak up water like a sponge if any happens to get in. They could also be lower in profile, but wider if that suits you better. This is standard practice on a lot of fiberglass and Kevlar canoes. They will often have ribs a couple inches wide, 1/4"-1/2" thick, made from slabs of foam with the edges beveled and then the whole rib is glassed-over. The half-ribs should extend across the flat bottom and taper out where they meet the curve of the bilge. It would be very unusual to need them to also extend up the sides on a stripper, since the curves of the bilge add so much stiffness. You epoxy the wooden half-ribs on top of the bottom's glass. That forms the core. Then you lay at least two strips of fiberglass over the top of them, extending a couple of inches onto the flat bottom on each side. Fill, sand the edges of the glass to feather them out, or whatever you want to help blend them in with the cosmetics of the rest of the bottom.
These will stiffen the bottom substantially, but maintain at least some flexibility on impact. However, they do make stress risers (stiff spots in an otherwise more flexible area) which would be somewhat more prone to deep abrasion or damage from rock impacts. Compared to adding a uniform layer of glass over the bottom, they are probably similar in bottom stiffness, but not so much in overall durability. Their job is more to stiffen than strengthen, but removing bottom bounce from the equation will certainly help preserve the boat in the long run.
When I built my big canoe I added half a dozen half-ribs, just to help stiffen the flat bottom. In this case, I followed a tip I read somewhere and used flexible plastic tubing for the cores. It was tacked to the bottom with a hot glue gun and then glassed-over. It worked, but it was hard to get the tubing to lie straight and neatly. In the long run, simple wooden cores or foam cores would have produced nicer looking ribs.