I use the Wilson 801245 amplifier with an external antenna. There are two antennas available and I've had success with both.
The first is an 18" magnet mount that I simply attach to a cookie sheet and lay on the ground under the motor, then run the cable thru the engine compartment into the bedroom. The other is a trucker antenna, Wilson 301133, which I mount to a 10' piece of PVC which I attach with bungees to the ladder on the rear of the coach. The cable is run the same as the 18" one.
Inside the coach I have a PremierTek ANT-P8025 attached to the amplifier and I use my phone as the hotspot....hope this helps.....Dennis