[Jdub]

You might try something like windshield sealent. It should dry clear.

Put a dab into each hole let it set up a bit, then put the assembly in, screw in the screws, and then help the whole affair stay in (as it is vertical) until the sealent sets up fully.

When dry, this stuff is essentially like bendable clear putty that is reasonably hard.

Failing that, I would either go oversize screws or try to shim a nut into the holes: the nut would need to have most of the flats shaved to a round. You'd stuff that into the hole and go with machine screws or ?.

Good luck,
John