I second (or third) the recommendation of going with a better antenna. Motorhomes make decent Faraday cages, so having something outside which can get a decent signal might be what is needed.
Car audio is so commoditized that if you buy a name brand, you should be good to go.
I feel old, because I'm still used to the times where people would spend $2000 for a car stereo only to have some hoodlum break in and steal it the next day, even though the faceplate might not be present. Now even the crackheads don't bother with the radios in cars. Plus, the factory one on my vehicle is as good as anything else out there, and one would pay more for a lifetime subscription to XM radio for the vehicle ($800 last time I checked) than the rest of the audio system.
