I do agree that some people have better luck on a taildragger setup.

If you do convert a typical trike setup as was suggested the mains should be just a tad forward. Typically when I convert one I place the wheel axle 1/2 inch in front of the leading edge of the wing. This have never given me any problems.

Instead of converting a typical trainer, how about a 4*40 or even the 4*60. I've "donated" my 4*60 to my club, as like you are, I am the chief flight instructor and intro pilot and most of the people I intro with have no problem if I set it up for very low throws.