Unfortunately in my neck of the woods, motorhomes also seem to be broken in, far too often. A friend in a local unit had his Airstream motorhome broken into, with the thieves crowbarring every electronic item out of the unit, and also crowbarred the basement storage compartments. Like many motorhome owners who tend to travel a lot, the folks had far more that what is kept in a typical trailer.
I think his bill for repairs was $50,000. A few weeks later after the repairs were completed, and while he had the unit in for service at the dealership, it was broken into again on the dealer's lot. Again more damage although not as bad.
To be honest, if I had a motor home, one of the first things I would do is go to one of the local shops here in town, that do alarms for business vehicles. While it may be a matter of a case of who can hear an alarm go off in a storage lot, I'd still spend the money as a potential deterrent.
'04 Classic 30' S.O.,'03 GMC Savana 2500,'14 Honda CTX 700