Your Roadtrek's VIN is going to come up as either a Chevy or Sprinter depending upon the model RT you are getting. You do not want "auto/vehicle" insurance. You want RV insurance which is very different - much broader coverage and usually full replacement - and a lot less expensive for the policy.
My Roadtrek is insured through Progressive. Before I took delivery, I called them up, told them I wanted RV insurance, they asked for the make, model and year of the RV and then we went through the coverage options. They had no problem finding the Roadtrek to insure as an RV and they knew that the VIN was going to show as a Chevy van and not an RV. The policy that they wrote is very specifically for an RV.