There were setbacks along the route such as letting the welding rod linger too long and burn a hole in the steel I was welding. That delayed things as I had to make concentric circles, waving the welding rod around the hole like Harry Potter's wand while I built up the steel surrounding the hole until the hole was filled.
I have't painted where I welded yet as I need to put sides on the compartment and the simple act of welding burns the paint off. Watching the paint in flames was quite entertaining! The original plan was for solid sides on the compartment. The power socket could go underneath the compartment. That would simplify things considerably. The cable needn't go through any complicated routes.
Checking the bodywork steel, it seems to be the same thickness as the vast majority of the lightweight sheet steel that I already have. It should not thus be a problem to fill the cavity left in the bodywork by the hillbillies. Certainly moving the welding rod as swiftly as Harry Potter's wand means I should be able to weld thin steel. My welding has definitely come a long way since I attempted to weld two steel conduits together and burned right through them.
Tomorrow's plan is to continue with construction of the compartment and possibly to demolish the old wooden compartment as well as removing the aluminum compartment door. Like as not, there'll be some hidden nastiness there that'll need to be dealt with. I might even need to move the bus closer to the power supply in order to do more welding.
I can kinda sorta see why people sniff at the cheap Harbor Freight welder. It is pretty slow to weld with. On the other hand, I'm not in any particular rush. If I can get the breaker box compartment completed by the time I return to work on Tuesday then I shall be elated.