I have the WeBoost Drive 4G-M installed in my B along with an outside antenna. To be truthful I am not sure it improves cellular all that much. It is installed up under my dash board behind the glove box. Advanced RV installed an on-off switch for me on a recent visit but I have not taken the time yet to see if it makes any difference by testing both ways.
Maybe it does work. I've noticed in campgrounds and such I, more than not, always had a good signal just about everywhere. Is that from the WeBoost or just better coverage year after year steadily improving? Maybe a bit of both.