Im here fossil. i dont know any independants. I have always gotten good service at Musselmans. I hear C and R trikes on east Irvington Road gives good service although I have not been there. They do a lot of Wing repairs and Wing conversions.
I'm also in Tucson and also new to GoldWings. I would echo billcarr. I buy my OEM parts at Musslemans'. So far, I've been able to manage all mechanical work myself. But, everytime I ask other GW owners for a reputable garage, C&R Cycle is mentioned.
The only caveat being that the owner told me (via phone) that they don't really like to do electrical trouble-shooting. They do seem to have a reputation for good mechanical work.