I was originally going to suggest making a structure that would bolt to
the ends of the main spar fittings, but that could impart stress on
those fittings that could damage them. The bed/carpet sling idea is
OK, except that you will be running the engine, not just moving the
assembly around. How about making a wood structure that "sandwiches"
the wing stub ( say about a foot outboard of the fuselage sides ) Think
of the "clapboard" that the movie industry uses before each "take" of a
scene. Cut out the shape of the airfoil between (2) 2 x 8's. Hinge
the 2 x 8's on one end and bolt them together on the opposite end.
Then extend a vertical board on the forward end of the structure and
put casters/wheels on the end. You could arrange the casters far
enough forward that you wouldn't have to add weight to the tail with
the wings removed. Make one for each side and maybe secure each
structure to the other one for rigidity. Of course making the whole
thing stout as hell and protect the wing. Might work.

Neal