The typically quite thin layer of fiberglass on the outside of a wooden canoe hull doesn't actually add much "strength" to the boat at all. Most of the stresses that a canoe hull gets in use are from forces pushing inward on the hull - beaching, hitting rocks, waves, and simply the weight of the paddlers forcing the hull down into the water and the water pushing back. These forces put the outside skin of the boat in compression, where a thin layer of external glass does virtually nothing to help. By itself, a laminate made of one or two layers of 6-8 oz. fiberglass saturated with epoxy is about as stiff as a plastic milk jug and would add about the same tiny amount of resistance to compression that an empty milk jug would have if you poke it with your finger. If you hit something, it will flex and basically just move out of the way while the impact shatters the wooden structure inside the boat (which is what is providing the actual resistance to compressive forces, no matter what it is covered with on the outside).
The true "strength" of fiberglass is its tensile strength. The strong, straight, thin fibers resist being pulled apart quite well, and better per ounce of weight than a lot of other fibers. In order to take advantage of this strength, you have to put them in a place where the forces they encounter are trying to pull them apart, not push them together or just bend them as happens from compression on the outside of a canoe hull. If you look at something like a stripper canoe with glass both inside and outside, it is the inner glass that is providing the tensile strength to resist compressive forces like rocks pushing inward on the bottom, not the outer glass layers. This is why the common rookie mistake of reducing the laminate on the inside of a stripper to save a few pounds is such a terrible idea. They may save a few pounds alright, but they'll probably also reduce the compressive strength of the hull (the strength that it actually needs out in the real world) drastically. They build a boat that does fine if you plan to put it in the water and jump up and down in it (which does put the outer glass in tension where it can contribute strength to the hull) but they will have drastically reduced the hull's ability to survive an impact with a rock. On a rib and plank hull, there is no inner glass, the outer skin (whatever it is) isn't in a position to add compressive strength and so that strength has to be provided by the wood structure. To boost it substantially with outer layers of fiberglass you would need to add enough glass to basically build a stand-alone fiberglass canoe hull - and who wants to tote a canoe around which weighs nearly twice as much as it should?
The one "strength" that a fiberglass outer skin can add to a wooden canoe hull is increased abrasion resistance, though the difference compared to canvas and a good filler isn't as much as a lot of folks think. In some ways, I suppose you could also say that the glass skin is potentially a lower maintenance covering, as you're less likely to have problems like paint cracks from the skin expanding and contracting - and the glass skin won't absorb water in use and add temporary weight to the boat. On the other hand, if your maintenance ever involves replacing cracked ribs or planking, the glass skin will make that much more difficult. You also want to be sure to maintain the varnish on the wood carefully. Water-soaked wood up against a fiberglass skin is a formula for rot.
So, in the long run, it's like everything else in life, there are trade-offs. With the fiberglass, you gain a few things and you lose a few things, but don't think for a second that fiberglassing the outside of a wooden canoe hull is really going to reinforce the wood or make the hull stronger, because it's just not going to happen.
p.s. In order to bury the glass enough to avoid sanding into it and weakening it, you will probably need more than two coats of resin - and the spar varnish under the paint won't do anything at all and may actually shorten your paint life by exceeding the proper coating thickness. Just sand the resin surface smooth to about 100-120 grit and paint the boat.
FYI - this is my fiberglass-skinned 1972 Old Town. I've been there, done that, got epoxy on the T-shirt and it came out pretty nice. Would I do it again? Probably not, as I think there are better options.