I do not have a long arm/quilt frame but I do have a very, very useful shelving arrangement that straddles both a treadle sewing machine and a vintage sewing machine in a cabinet. The arrangement extends from the wall, outward. I designed it and DH made it. It might give you some ideas that would help
Please forgive me but there are no pictures. I have not figured out how to get my Mac's or my iPad's pictures loaded onto the QB. I promise myself that will be someday soon. Another gracious QB member has volunteered to hold my hand and walk me through.
The "thing" has long legs that morf into the support posts for shelves. The first shelf holds quilting books. The next shelf holds sets of the plastic drawers I found at various stores - on sale, natch. We decided the sets of plastic drawers allowed me to see what was being stored and made it easier to get to things. DH made sure it will hold a lot of weight and is very stable. The "thing" extends from the floor to almost the ceiling. DH made me S hooks that will hang off the support pieces and I surprise myself at how useful those hooks are.
I like using vertical space and a set-up like this one allowed me to arrange that space just where and how deep and how tall I wanted it. (I do not hit my head when I am sitting at the machines below the second shelf. Good thing because I am clumsy! The first shelf with the books is narrower than the one above it so besides not crowning myself, the books are just a reach up for me.) The depth of the shelves wound up to be whatever does the jobs I wanted done. I also have spotlights hanging from the bottom of the first shelf that allow me to put light just where I want it. The wall space between the floor and the first shelf is open so I can have something attached to or hanging flat on the wall.
Granted, this is not a lovely, elegant organizational piece but it does the job and the design can be manipulated according to need. Function is important at my house.
I hope the above makes sense. Again, sorry about the "no pictures" problem. Please do show us what you finally decide on. I, for one, am always interested in a better way from one who has done it.
Pat