First let me compliment you on the "back country" engineering. All I would add is duct tape to give it an east Texas look.

A search on tailwheel problems indicate failures are somewhat common. Failures include broken springs, mountings, tail wheels, steering chains and linkages.

These problems are not unique to the Kitfox. Discussions on tail wheel failures on other aircraft types are quite common.

With that in mind it would be advisable for all builders to pay special attention to the tail wheel assembly and mounting. Certainly, larger bolts and brackets are high on my list. There is a lot of strain on the mountings particularly when doing turns on rough fields. When the tail wheel turns there is a lot of torque on the spring assembly. Upping the AN3 bolts to AN4 is a small weight penalty for a big gain in strength.

JP