Same problem - highway speeds/hot weather are the worst.

In the meantime I did some reading around and am about to try one suggested fix -a one way crank breather - the argument being that the extra unwanted air drawn in by the breather on the compression that then needs to be expelled out the breather on the power/intake stroke thereby circumventing the air fogging issues. Its cheap so I'll give it a shot and report back to the list.

part no. JP cycles #400-538

Chris