Ice dog I too suffer from this on the turbo trainer, glad you posted as I probably would have not, anyway I have found also to get out the saddle which relieves some of the numbness for a while.
I have also had to play with the fella to get life into him, which helps but this can be done in the quietness of your own home.
I have not had it on the road though, but if I do, im worried what some poor folk would think, having my hand down my shorts playing with myself!!