Believe it or not, the rubber bands work pretty well. I don't think there is a lot of force pulling outward on the wings. Just make sure you use some epoxy on the j-bolt threads and that they have no nicks or burs. The only problem I could see is a weak or damaged rubber band that fails. If you aren't confident in the set-up though, a lot of people have done nylon bolts.

One modificatin that I strongly recomend is getting rid of the stock pushrods. They constantly change length with the temperature. It can be a real pain re-trimming the plane all the time. I'd go with solid 2-56 rods, 4-40 rods or carbon rods, etc.

While I've never doen it myself, a fuel tank hatch might not be a bad idea.