What load capacity should a ladder have for A/Cs?

When I put the Atwood on our first trailer I grabbed some pallets and trash 2X4 and built staging in the back of my truck that was parked as close as possible to the trialer. If I remember it was only two levels to get it up on the roof. The wife and I lifted it into the truck, then up one level, then we stood on the first level and lifted it to the second and finally up on the roof.