mount it on a board, mount the board on the side of the bench with hinges. When in use swing it up on the bench top, when not using it swing it down, if the bench is hollow on the end the motor and wheels will hang under the bench top.

Or, if you don't want to hinge it, what about drilling 3-4 bolt holes through the mounting board and your work bench. then put it on top, and slide the bolts through to keep it in place.

Not sure what a pedestal/cement bucket saves in space over a workbench, btw.

There is a hinged contraption for kithen-aid mixers that lowers them into the base cabinet and brings them up to countertop height. That might work because them little mixers are heavy so the contraption should be too.

Get an old 10 inch or 11 inch brake drum or disk rotor, the bigger the better. Weld a 2 or 3 inch pipe to the center of the drum. weld a plate on top of the pipe. drill
holes and mount your grinder. i have 3. works like a charm.
your grinder is heavier than your stand. It is stable to a point. If your doing heavy grinding put your foot on the drum to hold it. the pipe will pull out of the concrete in time unless you drill holes in it or pin it.