I did this with a 60 size Ugly Stik ARF. Drill a hole in the lower leading edge/bottom of wing for a 1/4" dowel at a slight angle upward toward the trailing edge. The dowel will stick out about 1/2 to 3/4 inch. Drill a matching hole for it in the bulkhead in front of the wing saddle. If there's no bulkhead there you will have epoxy a piece of 1/8 or 3/16 plywood across the fuselage for the dowel to fit into. Epoxy the dowel into the wing, and you may also want to strengthen the joint where it meets the wing by epoxying a piece of plywood to the wing bottom.

The hard part about this is getting the wing dowel to mate up with the hole. Here's a trick I came up with. Before you drill the hole in the wing for the dowel, drill a 1/8" hole about 1/4 inch deep. Take a pencil and carefully strip the wood off until you can get a piece of lead about 3/8 to 1/2 inch long. Put the lead in the hole, set the wing on the plane, and the lead will make a mark on the bulkhead where the dowel hole will go.

Du-bro makes a wing bolt kit that comes with the bolts and two plastic brackets. These are bolted to the inside of the fuse to mate up with the wing bolts coming through the wing trailing edge. Remember to reinforce the wing where the bolts go through with some plywood.

It takes some time to get all the holes to line up at the same time, but it's worth it when you don't have to mess with all those rubber bands. Good luck!