Here's how I did it:
Umbilical cord hook up - iRV2.com RV Photo Gallery
This allows it to be reached without messing with the tailgate or crawling in under the rig. Be sure not to put so far forward as to prevent the umbilical cord from extending to far when turning. You can buy a bracket for mounting it, a couple of self tapping screws vs drilling bigger holes.
Also note the hookup for our breakaway cable makes hooking it up very easy and attached the vehicle not the hitch and many do. Again it must be placed so and not to stretch and activate the breakaway switch when turning the tow vehicle.