You just posted exactly what I have been considering. Placing two far enough part, side by side and a roof over them. My biggest concern is definitely the heat and the condensation. I live in a area that gets very hot and humid in the Summer. I know equipment in enclosed trailers, especially dark ones, literally bake. I was talking to someone today about them that has access and can deliver them.
Another concern of mine, mostly that I just got is how they are going to look. I see people on YouTube using Harbor Freight paint systems to paint them which seems to really make them more palatable to look at. That is semi important to me. Again though my biggest concern is even if I plan a roof, I would probably still plan to ventilate them somehow. A couple fans maybe, like one intake and one exhaust on each.
So my question would be what did you neighbor use for base? Concrete all the way, gravel all the way, a mixture perhaps?