In most parts of the country I suspect most people would recommend U-Haul because they do a ton of installs. They tend to be fast and generally cheaper than their competitors, probably because they get a lot better price on the hitches, based upon their significantly higher volume of installs. And their higher volume means less overhead per unit sold.
But a word of warning about wiring installations in general. Most four cylinder cars have only a four wire harness provided by the factory (left, right, running lights and ground). So the installer will need to run a power line from the battery & isolator and a brake line from the controller, bringing you up to six of the seven possible wires on the seven pin connector. The seventh wire is for backup lights, and on most newer SUVs (and some other cars), the backup lights are on the rear hatch (or trunk lid), where routing that additional wire will add considerably to the install cost, due to the time involved. Most installers will only quote for the 4-pin conversion and running the battery and brake wires, as adding in the cost of wiring for the backup lights will scare most of their customers away.
My impression from Craig (which may be mistaken) is that, for Camp Inn trailers, the most basic battery isolator and brake controller are adequate. We bought the more expensive proportional controller for ours (since we live in a mountainous state), as it seems to be harder to accidently lock up the trailer brakes. I've never run across anything about one brand of controller being better or worse than another, so I suspect they are pretty much a commodity. But then others may have put far more thought into the subject and have some specific preferences...
