I think that's easier said then done. Not everyone has a local machine shop. I have no idea where I would go to get that kind of work done near where I live. It's not exactly like driving to the nearest 7-11 and getting a gallon of milk. Probably cost a lot more, too.
I live in a low population rural area, and there are a couple around. Honestly I've never had enough of a problem with undercuts to investigate but other work I've had done was reasonable in cost.
Y'all might contact Clay at TSS (Telescope Support Systems) they might be willing to do custom stuff. Especially if it looks like there is a volume. Bigger problem might be lenses in the barrel tho.
Lenses in the barrel are the real problem. I have no interest in dealing with an undercut barrel with lenses in them as it is certain that upon reinstallation, I will end up with optical misalignment.
However for those EPs with no optics in the barrel, why not just buy a few cheap MAs or Plossls just for the smooth barrels and switch them out. OK, assuming you can find any sans undercuts. You might have to buy a few to get matching threads but it seems that would be worth it to some people here.