I've done this conversion on my Big Stik 60. You'll need to use a piece of ply and create a landing gear block to epoxy inside the fuse and yes, you need to reinforce it with triangle stock. I also used blind nuts so that I could retain use of the stock screws used to hold the gear in place. I placed gear block just behind the former so that the gear is basically aligned with the leading edge of the wing.

I went with the approach to link the tail wheel to the rudder. If you haven't already glued the rudder and stab in place, this will be much easier.

Having done it, I would say while it looks cool, it wasn't worth the effort. Plus the ground handling isn't anywhere near as stable as the nose wheel setup. If you do go this route, I'd recommend the approach to use an additional servo for the tail wheel as shown above by Diglivin and Y connect it to your rudder servo. This way you don't need to butcher your rudder and stab with the tailwire.