I would buy it, my 2013 Coachman has been used 4 times in the last 2 years due to health and hospital and eye appointments. FSH and always dry on damp checks.
Unfortunately Hutch as well you know (or at least should know) that just becasue one particular caravan from a manufacturer has been a good one does not guarantee or necessarily mean another van from the same manufacturer will be as good. All UK manufacturers have a pretty abysmal record of consistency.
I would consider it and I would also make any offer to purchase conditional on the outcome of an independent (i.e. AWS) engineers pre purchase inspection and report being satisfactory to me.
If the seller is unhappy about you having an independent inspection carried out, ask your self why, and consider the possibility the seller knows there is or could be a problem. If they have nothing to hide then they should be ok with having it inspected.
Do proper due diligence checks for owners registration, and if there is any finance outstanding on the caravan.
These checks are worth the money they cost, becasue with a private sale you have very little come back if anything isn't right.