My opinion is that it's easier to repair simple built-up models than most foam-based models. As long as you have Hot Stuff and packing tape.
My suggestion on how to proceed is pretty well documented. You want a simple model that you can repair, and provides adequate performance. Most trainers that use vintage engines are absolutely terrible. I have used a balsa clone of a SIG Skyray 35 for many years now - nominally the same airplane, for about 25 years. I flew it with several vintage engines and while I could get it through complete stunt patterns, it took a lot of effort and, not to be immodest, I was pretty good at model airplanes long before I built the airplane. It could be done but the skill level required was very high. I replaced the engine with a modern engine, and it was like gravity was turned off, it was so much better. The airplane is fully capable of winning any Advanced contest in the right hands, and I think my high score with it is up around 560 points.
The other thing was that the airplane started off with the stock kit parts - i.e. lots and lots of lite ply, which is both heavy and relatively weak, and also has no "give" to it. The first time it crashed, almost every rib in the airplane broke, and there was no fixing it. I rebuilt the airplane with balsa parts, and it has since crashed at least 40 times, and most of those resulted in no more than a damaged prop. The light wing made it perform *slightly* better, but it was vastly more robust, and most of those crashes resulted in no damage other than the prop. I had to rebuild it a second time, because the Monokote had turned to glass in 25 years in the warm California sun, and just crumbled in a light pancake. Any time it was damaged, I just glued it back together, right at the field, and flew it again.
My suggestion is a medium-sized profile airplane like the Skyray 35, Flite Streak, Medic, or similar built from normal balsa with normal techniques. Elevator-only is preferred, because it's easier to trim, and getting it trimmed (particularly without any help) is critically important. Cover the wings and tail with Monokote/Ultrakote. Finish the fuselage with epoxy. Do a neat job, but don't go crazy - because you really want to build 2-3 of them at a time, all the same.
Power the airplane with a *stock* OS20FP ABC or 25LA. When I say stock, that means *all the parts that came with the engine*, *exactly the way it came from the factory*. If you can only find a 20FP or 25LA RC engines, that is OK, get the stock CL venturi and stock needle valve/spraybar assembly from Tower. You probably only need two engines, but set up all the airplanes to be able to switch them easily from a broken airplane to a OK airplane. Use a *stock* APC 9-4 propellor, and get a lot of them. Make up a couple of sets of .015x60 lines.
Build and set up the airplanes and engines, and *take them all to the field*. Pick one, start flying it. Don't hold back, push yourself to learn the maneuvers. If you crash, DO NOT pack it in for the day and go home. Save all the peices, put them in a bag or box and put it in the car. Get the next airplane, check your lines, or replace them, and just keep going. Continue until you are out of time, or out of airplanes. Take everything home, and fix them before next session. If you have a problem with the airplane, say it just won't run, put it away, get another one, and keep going. If you run out of airplanes before run out of time, then, take a box with repair parts (like Hot Stuff, 1/64 ply, packing tape or FAS-CAL, saw/knife/sandpaper, etc) and fix the airplane with the least damage. With thin Hot Stuff, you can just push a lot of breaks back together, have all the fibers merge in a perfect splice, and one drop of glue will fix it almost to the point you can't see the break.
The key is to *just keep going*. The tendency I see over and over is that beginners/novices encounter one problem, then just give up, and try to fix it for next weekend. That's the worst thing you could possibly do, because it both wastes your time, and also, makes you so concerned with crashing and maybe losing another week, that you don't try hard enough.
Brett