Yet another vote for the RVI2 system. We move ours back and forth between a 98 Jeep Wrangler rock crawler and 2007 Grand Cherokee depending on where we are going that trip.
Works great in both vehicles, responds super fast for emergency braking, and never had a problem with battery drain even after back to back travel days. Definitely get the carry case to safely store the unit when not in use.
The wireless remote is wonderful, system is super easy to install, and doesn't take up very much storage space when not in use. If I only pulled one vehicle, and did so pretty much all the time, I'd go with an installed system. But if you switch vehicles at all, or only pull a vehicle on vacation, the RVI2 is the way to go.