Tear'em down and build them up.
From this one I think I am almost done with the tear down. I cut out about 200 pounds of bent metal and broken welds, all cross members, tongue and hitch.
I am going to add at least 400lb of reclaimed steel, adding about 2 feet of length.
I am reusing the axles, springs, wheel assemblies, most of the frame, fenders, about half of the original wood, some of the wiring, even reusing the old U-bolts I had to cut as tie downs.
This is after the chain saw got it.
Miller 625 plasma cutter, impact wrench
A few more hours of plasma cutting and grinding.