Sounds like you have some nice set-ups..
Yes the XQ can be charged via usb.. I'd take the battery out of the XQ and use the usb with the battery in the charging base vs charging the battery while it's in the unit. It may be fine to just go from usb to battery in unit, not sure.. However, the battery lasts a pretty damn long time if you are scanning with another unit and have the XQ on standby and only use it intermittently. Longest I've gone is a bit over 6 hours, and still had battery left.
Edit: I just looked at the manual.. From what it says, and doesn't say, my guess is that you have to use the charging base (plugged into a USB charger of 2 amps or better). When you run the cord from a computer's USB right in to the unit (as when downloading video), look into the eyepiece and you'll see two options.. use as flash drive, and use as power. Manual says when you choose use as power, all it does is power the unit, not charge it. So my guess is the unit itself doesn't have a charge regulator, and therefore you must use the charging base. Nothing is said about plugging the unit directly to power, my guess here is that it would just power the unit and not charge the battery. And.. after I wrote this I noticed it says not to use any other charger than the Pulsar one.. To me a usb charger is a usb charger (as long as it's the proper amp rating), but theirs must be special..
USAF retired too... and yes.. thank God!