Body off frame is never something most wanna tackle but it's not undoable.
Once its off repairs will be easier and alot nicer results too. Otherwise the fabricator will struggle with that repair from underneath..especially the area where theres pipe intersecting rectangular etc.
Myself, i'd copy the frame and its mounting if I ever had to go that far....saving the bent square tubing neck (hitch) part...not alot of people bend that stuff. It also could be replicated in round though.
Sounds awful doesn't it? It isnt for a good fab guy.
If you do it....have it powdercoated, so down the road 40 years someone else wont have to redo
The holes do look bad though and i'm sure more is hidden. Wish I had better news.....Bruce