I have been looking for a CHEAP second control head for my IC706.   I currently have spots in both my truck and OFF-ROAD POPUP for the ICOM706 but I am wearing the radio mount out moving the one ICOM706 I have between the two places haha...  Same thing with my TARHEEL screwdriver antenna.    I can move it between the truck or trailer as well...
I think I could solve the whole thing by installing a long CAT5 control head cable with disconnect plugs between the two units and maybe leave the ICOM main unit in the truck.   I am about ready to install my dual battery banks with one 300AH on the trailer and a second 300AH setup in the bed of the truck.  When camping they can both be keep charged up interconnected together with a 2-cond cable hookup from the trailer.
My TARHEEL antenna works better on the truck with all the metal ground plane around it.  My backup HF antenna is a short 3-inch triangle  tower I can swing up on the back of my trailer about 12-feet which will get me up about 25 off the ground with a PVC pipe in the middle and I hang a windom off center fed 80-10 wire antenna off that.  Throw the ends up into trees.  My antenna is more of Vee instead of Inverter Vee.  It does work pretty good however - Better than the TARHEEL on 80 and 40...   I get alot of bad looks from the RV crowd however...
Just need to find a CHEAP junker ICOM706 for sale for parts only and steal its control head haha...  
Roy Ken K9PHT