While I try to do this when possible, sometimes it is impractical.
FWIW, I do not want to have to replace any expensive electronic components but the easiest way to avoid this issue if you have to weld on the frame is to have a GOOD ground on the part/area you are welding and have your ground clamp there rather than on some misc. bolt.
When the ground is too far from the localized welding area or is insufficient (paint, rust etc. on either the clamp, the metal or both), the current will "search" for a better ground. (A floating ground is a very BAD thing in this situation.) I have used this method many times with absolutely no damage or ill effects.
FWIW, I have electronic disconnect switches just inside the coach door but if there is ANY minor draw, the chassis battery will not disconnect. I can disconnect the coach batteries but the reality is that I will be adding a secondary group of disconnect switches in each battery compartment at each bulkhead so that I can disconnect both ground and positive terminals.
I would still insist that the local ground connection at/near the weld area is as good/clean (sanded or ground down) as possible and the welder clamp be in good condition and clamped to this area.
Just my $.02...
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