I have a twin mover on ours, to be honest a single mover on a twin axle especially when manoeuvring on grass is not that good.
The twin motors are far more effective obviously as you're moving two wheels instead of one.
But unlike a single axle mover, a twin mover only turns the wheels on one side when turning left or right, whereas a single axle mover will turn the wheels in opposite directions when turning thus making it turn on the spot.
We have an E-go mover with auto engage which I find to be really good. Downside is they are quite expensive mine was about £1500.00.
Depends a bit on just how much manoeuvring you will need to do.
A previous caravan of mine was a twin axle, initially got a single wheel mover. The van weight was within the limits for the mover and it did perform the job, but only just. That was in the main part due to my house and drive location. I used the mover to bring the van up a short but fairly steep driveway onto a narrow private road in front of my house where it needed to turn the van 180 degrees ready to be hitched up. Couldn't use the tow car to do this because the road was too narrow, and close proximity of a busy main road. The single mover did the job but I felt it was straining a bit coming up the slope and the 180 turn involved a bit of back and forward turning, more like a 10 point turn rather than a 3. Eventually bit the bullet and upgraded it to an all wheel unit ( used Powrtouch, and already had an agreement with them regarding the upgrade if the single wasn't suitable). Made a big difference but if it hadn't been for my home storage layout I probably would have kept the single unit.
All wheel unit definitely the best if you can afford it, single unit ok for more limited use
I have a single mover on my twin axle and I can honestly say it's about as much use as a chocolate teapot unless you only want to go straight. I can't remember the name of it, it might be a Bulldog or something like that made by a firm in Coventry if I remember correctly.
The guy I bought the van from told me just couldn't stretch to the price of a twin mover when he bought the van new and I always find myself cursing the bloke every time I try to use it which is not very often
I have a double movers on my twin axel, tried single and failed miserably , awful manoeuvring and tricky on uneven ground if one wheel was off the ground when rolling on the levelling ramps.
My last van had a Reich mover fitted on rear of wheels single axle shock absorbers in front never ever faulted in 5years.
Ordered at Cottingham caravan show fitted by Reich UK at my home in 4 hours with two tea breaks.
Total cost £1,090 for auto engage/dis engage model.
It rained for three out of the four hrs but most of time guy was under van and rest of time in van except for drilling and fitting isolator in battery box.
PS he even fitted heavier multicore battery cables and terminal battery connectors with all cable ends soldered.