I see photos online of people using mirrors similar to yours with Ergon grips.
Note the external clamp rather than the internal clamp.
But, I'd imagine you could modify your setup to work.
If you come up with a good idea, then you have to know someone around that could help you with the modifications.
And, if it doesn't work... the hopefully it wasn't that expensive.
If not, then it is time to get a toolbox with a hacksaw, a few files, screwdrivers, wrenches, etc.