This has me hopping mad! I've been a USAA member for a LOT of years (40+) and always had my TT insured through them. Now they're out of the RV segment and have partnered with Progressive for that. ...
In Texas a truck camper is consider cargo and is covered as such by the trucks insurance when on the road. No license plate either. When stored at home the truck camper is covered by the home owners policy. I did drive by my insurance agents office and let them take a pic and record the serial number.