Lynda,
If your motorholm is of the type with a ladder to the roof at the rear you should be able to mount it there.
Otherwise the winch could be used in the manner of raising a yard up a mast on a boat where the winch is at a convenient height and the cable passing over a pulley at the top of the mast then down to a sling or a spreader bar attached to the seatpost and the handlebars.
If the rear section of the motorholme is sturdy enough the pulley could be attached there above the rack.
Lacking such strength a substitute sectional mast could be fabricated, perhaps from two 4 foot tubular sections.
The lower section might slot into a traverse T section tube with a footplate for you to stand on to provide stability. Somewhat after the style of a quality bike stand.
Two points to bear in mind.
(1). The pulley will have the weight of the bike and an identical downward force from the winch.
(2). If it all seems a little agricultural, an orraman is a handyman on a Scottish farm.
Dave
"Give me a lever long enough........."
