Hi Leonard,
There's no hard and fast rule about what accessories a second-hand caravan includes within its purchase price.
Buyer beware is the long standing adage.
One hint,though, check thoroughly before you agree to purchase on such things, and if they are not included, then haggle. a dealer will typically pay only about 60% of the list price for most accessories items, so they have quite a lot of lee way, and would be fools to lose a sale for the want of a