I'd like the same feature for the opposite reason: Searching for places to stay in our camper van often show great looking places that are for motorhomes only (ie, they have no on-site toilet/shower facilities).
I know I can filter results using the "Toilet block" check box, but I still feel like it would be easier for all involved just to separate motorhomes and camper vans.
To my mind, camper vans are _usually_ smaller and do not have their own toilet, whereas Motothomes tend to be larger and with their own facilities.

This is also an issue for booking. It is very easy to book a pitch thinking it is for a motorhome to then find that it is campervans only. The search for motorhome pitches needs to exclude these. Campervan searches can still show motorhome pitches but motorhome searches should not show campervan only pitches.