That HF start is something I never considered would be an issue. I assumed wrong I guess but that ground clip seems like the easiest solution ever. I have a spare board so I am willing to give it a shot both ways. What is the down side, rougher/larger initial arc spot?
Heat really doesn’t seem all that high. If a sheetmetal or aluminum (worst case) shield was added at the tool holder, just a disk or a shape that extended past the tool holder and z tubes by an inch or 2. wouldn’t that be enough. Doesn’t the shielding gas carry away a lot of the heat? I carved up a few painted fenders and I don’t remember much heat at all. Total affected area was about 3/4 wide and didn’t effect the paint past that distance. The feet would need some shields as well or just pipe clamp the conduit to the table, or just use conduit all the way to the floor, and pipe clamp on the work surface.
This is all just speculation at this point it has been at least 10 years since I touched one but i am getting excited to try it.