If you want to fix it right, you'll have to cut out the rust and weld in new steel. Sounds like this is what you have in mind. If you need a lot of patches, the cheapest route probably is to find a parts car and either swap bodies or cut the panels you need from the parts car and weld into your car's body. These are not valuable vehicles unless in pristine, low-mileage condition, so try and balance your sentiment against the cost and time needed for repairs. Some repair panels are available from BJ's and Raybuck and likely others, but if you need a lot of complicated patches, buying a parts car may be a better route.
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination ATs, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
ECO Green: '15 FCA Jeep Cherokee KL Trailhawk