I know you can get the GPS antenna under the rubber change area on the center dash console, could the XM antenna go there as well?

I don't have XM but I do have a GPS anti-theft tracking device on my F150 that uses a similar antenna. When they installed the GPS they put the antenna on the brace that runs under the change tray. There is room for only one antenna there. So I took a metal light switch plate, drilled a hole in the brace and bolted the plate to the brace and set both antennas on the plate. There is room under the change tray for all of this and reception is great on both units.

You can put xm or sirius antennas there but your signal will drop out. Always try to put Sat radio antennas outside...

if you want to put the xm antenna in side, i always recomend using a xm home antenna, they are a little bit larger and they have a lot less drop out

note: some area's have a lot more terrestial repeaters than others, they will not have as many problems with drop outs when the antenna's are under things as much as places that are out in the middle of nowhere that dont have any terrestial repeaters and rely on the sats alone