Re: Neck on RG2020 and sanding it down.
I shaved an Ultra Radius neck down and it's pretty cool. The nut width on the Radius Ultra necks is narrower than the standard Wizard. So mine doesn't feel like a Wizard, rather like a custom hybrid shape. I did it for a customer and liked it so much, I had to do one for myself.
Pay no attention to that cross section photo in the old ad. Heck even in that pic you have a good 1/8" you can remove safely. But I don't know why that truss rod is in there like that. Your 2020 is going to have a truss rod like the Wizard/Jem shown in that photo. The rod in the Ultra apperars to be a traditional rod with a filler strip, but Ibanez does very little (if anything) that way.
At that time, (89-92) some Ultra necks on Radii were extra fat and round, like a fat Les Paul profile, even bulkier than old Roadstar necks. Those necks had smaller frets, too. That's not the same as the current Ultra neck, OR the original Radius necks. I think the "Ultra" name has been used on at least THREE distinctly different necks: The original Radii (42mm nut) the fatback Radii (42mm nut) and the RG's (43mm nut) I believe the RG Ultra has the same thickness dimensions as the old Radius necks. The nut width makes it feel different, and have a different profile.
Anyway carve away if you want. You should be fine, just keep measuring.