I just wanted to post pics of the tail wheel I constructed using a paper clip. I once mentioned in another post the corner stone for a steerable tail wheel is the black triangular mount screwed in to the pipe. I had an extra one but I think any average builder can construct this piece out of wood stock. The type of paper clip I used is in the pic below. Notice the design of the clip. Its thicker than a large paper clip so be careful not to buy or use a thinner clip , it may bend when landing or taking off.

Kudos to you for coming up with an inexpensive tail wheel rig. However, I don't think that it will be effective for the following reasons:

The distance between the bottom of the tail and the wheel axle is a bit long. I look for that set up to fold up in a hurry. Your set up is questionable even with a material designed for the purpose.

The steel wire used in paper clips is soft with very low tencil strength, in other words it does not have much spring or spine to it. It simply bends too easy.

When you straightened out the original paper clip you introduced metal fatigue into all of the former bends in the clip, thus severely weakening the integrity of the wire. You would not get more that two or three opportunities to straighten your bent tail wheel before the wire would break all together.

Nice idea, but I would stick with what your LHS has to offer.