I put this under class A as I believe those driving Motorhomes ( especially longer heavier w/tag axles) would be paying much higher tolls than fifth wheels or travel trailers, and perhaps more likely ...
Denver just goes by Axle - but here is the catch - my toad has an EZ pass and so does the MH. The toll is the 2 axles of the first vehicle, then each axle is a full vehicle toll after that. My MH=1, tag=1, Jeep=2, so I get hit for a total of toll X 4, then the EZ pass for the Jeep takes a hit making it 5.