I purchased a used ATV lift from a pawn shop, for 40 dollars. I didn't like the tiny wheels, So I went to Harbor freight, bought four 4" wheels, and I welded them on. it will roll over gravel, door jambs almost anything except stairs. It fits directly under my pins, so it slides pins right thru doors. It has tie down hooks built in and a bottle jack for lifting. wheels are rated for 1200 pounds, the lift for more than that. the whole thing weighs less than 100 pounds.

its this plus wheels. VVVVV

http://www.afabonline.com/images/Lift-Cln.gif

those bottle jacks can leak, but are easily replaceable. a seal would have to rot out, because you're not putting enough weight on it to blow it out. there's less than a cup of fluid if they do go.

http://www.harborfreight.com/4-ton-hydraulic-bottle-jack-66450.html