I've done a ghetto pulley for kayak, its okay but the pulleys are pretty rough. In that space you could prob reach up high enough to use two hooks, lift first wheel up to highest one, then other wheel onto second hook. Or against the wall.
Paulie is right on the pullout strength, look up a chart for the metal thickness and screw size. I put up some shelves on the exterior of the same shed with ~5mm metal screws through the battens, theoretically each had 300kg pull out strength. So I used 6 for each shelf.