Stinger hitch too long, want to shorten it

RM advises to not drill a hole in the opposite direction. Call them and see what they advise for your plan. I'm thinking like some minimum distance between the 2 holes.

Why do you want to shorten the tow bar by a few inches? Fill the original hole with what? Welding might not be a good idea.

I'd probably just mark the old hole to not use. You could also buy a new stinger in the future, about $150.

What will happen when you make a sharp turn after shortening your hitch? Make sure you'll still have enough room to keep from the towed hitting the tow vehicle.

I emailed RM after I registered the product online with my question. I asked for their opinion, not advice.
They responded promptly that they cannon give advice on modifications that they have not tested.
However, the email stated that they knew of others that had successfully made that modification.
It was more than I expected from an email communication.

Roadmaster drilled me a new hole plus cut the tube off by about 4".

:) Hi, I bought a longer hitch shank to clear my tailgate. (18" versus 12" shank) I had it re-drilled and cut twice. Each time I had the new hole drilled 2"s back. First time I had 1" cut off of the end and the second time I had 2"s cut off of the end. Both times I bought 3/4" rubber plugs and forced them into the old hole so it couldn't be used.

Drill the hole. We've been on a farm for years and have had to modify a lot of stingers on various hitches for a number of specialized equipment pieces. When you drill the same sides where your present holes are, the drill goes through the square stinger in the center. This area is the point where the absolute stress in the piece is the the least so there's no issue on over stressing it. Further, since the stinger is shorter, the overall moment arm on that part of the hitch is less than that you get with a longer stinger arm. When you drill it, be sure to get the holes in the right spots. You don't need an elongated hole so the pin will fit.

Structurally, pigman1, is essentially correct.