Found this post on the forum...might contain useful information about an alternative CB radio for the interstate.
http://www.valkyrieforum.com/bbs/index.php/topic,9185.0.htmlAs for the handheld radio on your bike...you should be ok with 3 items you mentioned connected to the cig plug. The XM or GPS are not large draw items. And really...neither is your handheld radio.
As for getting it to work with your system...you are pretty much out of luck. It will have to be run as a separate beast. Since you already have your XM running through your Aux input, you will not be able to use that. So, separate helmet speakers would be the only way. The only problem with that is...there isn't much room in your ear pocket for another speaker.
I know...not much good news...but you know...that is how it goes sometimes.
Joe