Avoid opening wall?
It is possible to surface mount a separate wood panel, behind your 'shelf system'.
wide enough to catch only 2 studs, and use many anchors to sheetrock or plaster for the extended end. Then you have limitless horizontal locations to mount anything to the wood panel. Choose wood thickness relative to weight.
Or, wider, catch 4 studs if heavy TT? full width? Depends on decor, ....
btw, brackets can go 'up' behind the shelf, rather than down, objects on shelf in front of them. and you can drill extra holes in the brackets with less final visibility.
It is possible to surface mount a separate wood panel, behind your 'shelf system'.
wide enough to catch only 2 studs, and use many anchors to sheetrock or plaster for the extended end. Then you have limitless horizontal locations to mount anything to the wood panel. Choose wood thickness relative to weight.
Or, wider, catch 4 studs if heavy TT? full width? Depends on decor, ....
btw, brackets can go 'up' behind the shelf, rather than down, objects on shelf in front of them. and you can drill extra holes in the brackets with less final visibility.