Insuring friends on our motorhome

We have a motorhome, a 2003 CI Carioca 5 based on a Fiat Ducato chassis/engine. We like it but it is not precious to us and to date we have not used it as much as we would have liked. We are planning a trip to Scotland in June using it but may well sell it after that.

Before that we would like to lend it to a couple of friends for a couple of weekends as they are considering buying a motorhome/campervan. What is the best way to get them insured on it? It will be on a 'bend it you mend it' basis so I will not be profiting from it. I think options would be to add them to my insurance (but I guess any incident would affect my future premiums) or they take out some sort of standalone cover.

Any advice or experience appreciated.