I'm trying to use a toggle bolt, but the combined thickness of the plasterboard (~30 mm) and the shelf bracket (22 mm) means that the toggle won't push through far enough to spring out and grip the wall. The longest toggle screws I can find are 80 mm, and they leave me around 7 mm too short.
The bracket is hollow metal, so one thing I could do is drill the outer hole larger so that the screw head fits through and tightens against the metal adjacent to the wall which would give me the extra mms needed to get the toggle through. I don't particularly want to do this for a few reasons:
a) aesthetics of leaving a big hole in the bracket,
b) possibly weakening the bracket,
c) making it difficult to access the screw.
Any better suggestions out there guys?