Tom,
When I was on grass in NC, I had a small riding mower that I used as a tug.
I built a steel V from square tubing that attached to the horizontal portion of the gear legs and attached it like a hitch to the front of the mower. Worked like a charm because you had a small amount of directional control. I will warn you though, controlling the tail requires lots of practice.
I now have an electric winch that I use to haul it in and its a downhill slope out.
If you don't want to deal with gas, an electric golf cart would also work.
I know its popular on this forum, but after rebuilding my tailwheel and seeing how fragile the upper attach of the tailwheel shaft is, I won't tow it from the tail anymore.
-Adam