"My question is has any one used a window mount antenna with an amplifier successfully?"
Those amplifiers are very susceptible to rf feedback. Much like a podium microphone with howling speakers. The issue is transmit energy getting back into the receiver and often shutting them down. Using a glass mount antenna may be asking for problems. Even though you spent a lot of money these things can be more problems than they are worth for the average Rvers tech level,. A roof mount antenna is far preferred with a decent ground plane which helps tremendously. The fiberglass/wood roofs do not provide good isolation. I have used metal duct tape on the outside of the roof and mounted the antenna through that with good success. In a car using the magnetic outside antenna on the roof (without a sun roof) can provide excellent service.
For the average weekender and as a telecommunications tech that owns a company that specializes in vehicle installations I can personally recommend the Wilson setup. Use a blue tooth to have hands free and you don’t need to remove the phone. Heck, even my aftermarket dash radio has blue tooth and it works well muting the radio and switching the audio to the speakers.
The gain specs for the Wilson are a bit lower but from first hand experience and using some very expensive test equipment it really has the best bang for the buck. If you want to get fancy you can run directional antennas mounted to your crank up antenna mast. I have several amps you are using and they have all been retired. The Wilson is also useful to grab and put in your car if traveling about in poor coverage areas.
Back to the window antenna. It will be a******shoot and may work fine, however if I had a customer asking me about it there would be as pays your money and takes your chance lecture. Most heed my advice since I have been doing this for 40 years.
H/R Endeavor 2008
Ford F150 toad >Full Timers
Certified Senior Electronic Technician, Telecommunications Engineer, Telecommunications repair Service Center Owner, Original owner HR 2008