I agree, I can't see how the lack of a reversing camera prevents anyone using their van. in a slightly different, but probably more important field, many commercial vehicles are fitted with reversing cameras nowadays but it would not (in DVSA eyes) prevent the vehicle from being used safely if the camera was not operating whereas a missing obligatory external mirror of course, would.A small company having there summer holiday are surely entitled to it! You are on yours so why not them? And how does a lack of a reversing camera stop you using the Motorhome?
Get the missus out to check you back if needed,