Strip of light, laser projection or whatever

Do you have a straight shot at it, or do you have to jack it into the shed? If it's pretty much a straight shot, get you some red marking paint from Lowes or Home Depot and paint a straight line onto the dirt for a reference. You can respray it if it starts to fade. You could install a flood light in the shed, above the opening on the drivers side, shining backwards so it doesn't blind you at night. Make a wooden wheel chock to go behind the drivers side tire where you want the trailer to stop, and paint that red too so you can see it.