Hi Austcamper.
Have you looked at the oversize Jockey Wheel which has a lever drive system(For want of a better explanation) that you operate with a long handle.
Essentially a manual drive on the wheel,and you steer and move the van easily by hand.
I have not used them.
Perhaps some other poster that has one might contact you or leave a message
Should be available from Caravan parts or similiar store
Regards
Seabug