Not sure about the lighting configuration of your coach but most the the HR/Monacos I've seen over the years are pretty much the same. There is a light above the driver's seat that can be pulled down/out and that should provide access to the roof (and also permits access to the Winegard TV batwing wiring). Once you're in the roof cavity you have all sorts of options on drilling a new hole for the antenna, fishing the cable to either the window pillars, etc.
Adam
2010 Neptune 37PBQ, 2019 Jeep Cherokee