The weBoost Drive 4G-X series had the best overall reviews when I researched boosters a few months back. Three different “outside” antennae were available in packages, magnetic roof-top, mirror-mount trucker and RV mount, and there were several other add-ons available tuned for the device.
The antenna that talks to the phone has limited range (so as not to interfere with the outside antenna), so the booster can be used either in the truck cab or in the camper, but not both. At this point my brain got caught in the “cab/camper/cab/camper” feedback loop, and I put the project on the back burner.
Let us know what you decide to do.