We use a Bulldog Stabilizer with our 1997 Bailey.
Having had an Alko hitch type stabilizer in the past, I would rather have the bar type any day. Easier to service and maintain.
Also we tow other trailers which require a greased towball.
It is a PITA to have to keep having to clean the towball when using the Alko Stabilizer.
If its a small caravan I'd save yourself the money & trouble. Load it up with correct noseweight & tyre pressures, take it for a tow & see what you think. It will probably tow straight as a die.
I also would not bother, stabilisers add to the comfort of the towing experience but little else, they don't stop instability, just damp the movements.
Without one you will notice instability earlier before it can develop to levels that potentially can take charge, and for one new to towing this is a positive as it hints that your are driving with too much vigour or the loading is not optimised. The downside is the ride will be a tad less comfortable as you will notice the van's every twitch, though I prefer to know how it is running rather than wait till it is overly apparent.