I was hoping to find some pictures, but no luck. I will attempt to describe what I did.
So, the weboost unit itself was mounted inside the camper. The outside antenna wire exited the camper at the very rear passenger side. I made a 1/2" hole (to fit the adapter ends... the wire itself is quite thin) in the wooden floor pack and sealed it with butyl tape. I left enough slack so that it was long enough to raise the antenna when the camper roof was up.
I used Veritas T-slot tracks and nuts from Lee Valley Garden tools (I also used this on the roof of both campers I have rebuilt - works just as well as Yakima or Thule tracks and is way cheaper) to make the antenna mount. The fixed end of the slider... one chunk of the T-slot track, was screwed/bolted to the rear pax Jack mount. The antenna itself I mounted to another section of T-slot track (I removed the spring mount from the Trucker Antenna for some reason I can't recall) and with some trial and error made the sections of track the right lengths so that the black top 6" or so of the actual antenna projected above the roof when it was down, and when it was up. Simple t-bolts with wing-nuts (I used 2 or 3 to make it solid) allowed for rapid deployment.
The extra wire for the antenna I stuffed between the camper and the truck bed when not in use. A couple of metal hooks screwed into the floor pack allowed the antenna wire to be secured so it didn't come out and look unseemly.
I hope that helps.