Campervan change of classification

Hi - I'm sure this has been covered extensively elsewhere, but I cant find the relevant discussion!

I have a VW T6 which was professionally converted to a campervan.  The conversion met all the DVLA guidance both internally and externally, with the sole exception of having no graphics on the side of the van. DVLA have declined to register it as a "Motor Caravan" on the V5 stating that the van must be "distinguishable" in traffic in order to change the V5.

Two questions - Has anyone else had this refusal, and possibly more important, does it disadvantage me in any way by not being able to change classification to "Motor Caravan" (for example speed limits?)?  If there is no disadvantage then I probably wont bother challenging it.

Thanks in advance