Instead of doing it like your picture, move the wires out onto the ends and wrap the ends with some thin brass strips and then wrap the whole assembly with fiberglass. That's how the cabanes on the Sig Smith Miniplane are built and they are very strong.

Or, make the ply the same thickness as the wire, cut slots in the wood, trap inside with some 1/16" ply on both sides and then glass it.

Or, if you are determined to mount as shown, use some nose wheel steering bearings bolted to the ply.

Don