I did it in a two car garage. I spent some time first on the garage - effective heat and a window AC unit so I could enjoy working on it all 4 seasons.

The basic process for making joints with repair panels in sheet metal is "stitch welding" which is basically a repeated series of tack welds until the joint is complete. This minimizes the chance of warping and burn through. To replicate spot welds, you drill one panel with 1/4" or 5/16" holes and fill with weld.

A MIG welder would be easiest to work with. Gas would heat the panels too much.

Suggest you get a good book on body work.

If you decide to tackle it plan on taking some time - a couple of years in my case.