Takes me back to the good old days.
When I started out I used to ring around the caravan sits in the winter and get some work to help me through those quiet and difficult times.
Caravan carpets and upholstery are no different to cleaning houses. Carpet is carpet and upholstery is made with fibres, as in houses upholstery.
the carpet tend to take a hammering in the lounge, but do tend to be man made fibres ,not wool, so clean up well.
As for your machine, its a simple fact about carpet cleaning machines, the bigger the machine the easier the job. If you got a big machine with big water tank and high heat, its loads easier ( and therefore more pounds per hour) than a small, 'have to keep filling it' no heat machine. On caravan sites getting hot water can be a problem.
But go with the caravan cleaning and as soon as you can get a bigger machine