Mud or wet grass grip tracks

I'd not worry. I've only had RWD cars (up to buying a 4x4) & rarely had problems. A caravan on the back is going to help traction

Presumably the weight of the van is going to add to the weight on the driving wheels and so you ought to be better off. We've been stuck several times with front wheel drive cars on deep, wet grass but generally there's a way round it. I wouldn't worry too much.

Two threads running again

Actually, no, a caravan on the back will not help at all.  On muddy ground a) the less weight you have the better b) the caravan itself acts as a drag, particularly if it also is getting bogged down.

I suspect you were just lucky with the BMW

Old strips of carpet are as good as anything at the first level.  Waffle boards are the next level up, but they take up space and cost, so are probably not worth it.

Take a long towrope.  If you can get your tug on to firm ground and then use it to attach to the 'van, it'll probably be enough to pull it off.

If the jockey wheel does not plough

If you like to stay on grass pitches, then the waffle boards mentioned will be a good investment. They are what 4x4 drivers use when playing in mud! Don't cost much, on the heavy side, but with proper use you shouldn't get stuck. We carry a pair on back of our MH, if weather looks dodgy, park drive wheels on them....no problems. Check out 4x4 equipment websites, £35 is what we paid for ours, so decent price. You want good ones, not cheap rubbish.

Weight over the rear axle will help but you shouldn't have a problem with a RWD car unless you're heavy footed on the throttle. 

We bought two plastic tracks many years ago in case we got stuck. Never had to use them as once you have the answer to the problem, the problem never turns up.

Probably a wise precaution for most people though, but if your caravan has a mover fitted then you can use that to get it off the pitch if need be. Certainly the only time we needed the caravan of a very wet pitch it did it without problem.

We saw reverse on a CL last year. Why the fool unhitched his car and let mm spin caravan wheels into soft grass instead we will never know. But we towed him out!