That is an interesting link. It finishes with saying if you wish to carry something you're not sure about then obtain legal advice. If they're not sure.....?!?!?
If over 3.5tons with a garage automatically meant Class 7 and was a goods vehicle, then it would have to have been plated and had a tacho from new. Surely any legal definition of goods would be the obvious main point, either you are a scooter salesman or you need it to pop to the shops?!
I also don't quite understand why towing a car or carrying a scooter or even push bikes are not essential to living in a motorhome. How many town centres are suitable for even a medium sized camper, making such additions essential to many?
My camper is based on an offroad truck and doesn't look to many like a camper (at least thats what I keep telling myself when no other campers wave back
), and at 9.5tons with small garage the two different places I've used for MOTing have asked if I carry goods, but one has twice said its for me to tell them what test I want, not for him to insist at all, and that Class 4 is any size of vehicle.
And if you deny them access to an area of the camper they decide they need to look in I'm sure they can refuse to test you.
Dougie's advice is the best though, and if the MOT station insist on Class 7 go elsewhere!