It might be worth looking into installing XM Radio's home stereo set-up. Though I am not sure how good that antenna would be, over the stuff that comes with these rigs' equipment.
My Monty came with a Quest 1000. It got ZERO reception, save a couple PBS and maybe a Christian or two station that I seem to be able to receive on the 1/2 time oven, without effort.
When I installed a Sony Home Theater System, I was able to pull a couple more stations out of the ether, using the wire antenna that it comes with, instead of that coax thing that came with the Quest, for FM. Haven’t tried much for AM, yet, though. It’s still not as good as the TV's AM/FMradio can receive. (I only bought that XM option to get the remote control to use in my TV.)
I do believe that you'd need to install an exterior antenna to guarantee reception. I haven't even tried the XM home system, yet because I'm still enjoying DirecTV, and don't feel the need to receive much radio. I suspect the aluminum framing on this Monty would tend to impeded reception, unless I sling it through the window and hang it outside.
Think of that stereo like having one inside a tin-foil hat.
Steve