As already been stated, you're not really boosting the cell signal. You're merely extending the signal into your camper. If the signal outside your camper is weak, you'll be extending that weak signal into the camper. You're just bypassing the metal shell of the camper that is obstructing the signal that is outside of the camper (weak or otherwise). Yes you still might be able to pick up a stronger signal outside of the camper with a higher pole mount antennae, and thus extending that better signal into the camper and receiver. However, I've found that by placing my cell phone next to a window that is closest and directional to the nearest cell tower (or even dangling it outside of a window) and using it as a hotspot, generally provides the same level of service you'd get with a whole external antennae/internal receiver/wifi transmitter set up and associated costs.
Look into
https://www.starlink.com/rv.
Expensive, yes. But you can turn it on and off as needed.