Be sure the installer does not use a diode box powered by your existing tailight wiring. The Express needs its own powered trailer light converter. There isn't really any amps left in the factory wiring. Using a powered converter box means all trailer lights are powered directly by your batter.
BTW - Uhaul installs the most hitches. Our local Subaru dealer even sends their customers that way. They probably also have the powered taillight converter you need. Another option is buying from eTrailer.com and doing it in your driveway. They provide instructions and videos for your hitch and wiring components.
