Mounted tach without drilling new holes

Here's another alternative for you guys who want to mount an aftermarket tach for great visibility, no new holes, and no hose clamps on the steering column. Sorry, description only...no pics available.
Back about 1970, I mounted my tach on the shoulder harness buckle/visor mounting plate in the top left corner by the windshield.
It worked great until the one time I got stopped by the local police telling me it obstructed my vision (it really didn't, but wasn't compliant to the law). I rewired it with a small plug connector so all I had to do to get the 'fix-it' ticket cleared was unplug the tach and stash the wire on top of the visor. Got the ticket cleared, plugged in the tach and drove away. Never got stopped again.