Back in the 60's when the 5.25 wheels were plentiful and the 4.75 wheels were getting scarce, 1/4" adapter rings were routinely used. They were tack welded to the rear hub and the clamp held the front ones in place. I would be hesitant to try to weld the adapters to the wheels. There is a lot more room for wiggle, you risk warping the wheel and you can get by with one thicker adapter on the drive axle.
