Anna
there are, I think, 3 suppliers for movers which fix to the chassis - Truma, Powrtouch and Reich.
Truma doesn't have a 'soft start' but Powrtouch and Reich do - this enables you to inch the van about to make hitching up simple. Powrtouch has a 5 year guarantee, Reich is 2 years. The motor on the Reich is away from the wheels, so it is a little more out of road spray. We chose the Reich simply as we were mpore impressed with it at the Caravan Show we attended in Birmingham. I don't think there's much between them at the end of the day.
As to draining the battery, we have a 110 battery and we've never had any problems with power, but then we always use sites with electric hookup and we charge the battery and overnight before any trips, but that's mainly to cool the 'fridge.
We have a Bailey Ranger 510/L which is lighter than yours but is too heavy for me and my wife to push with comfort, with our weak backs, especially on wet grass. Our drive is awkard to navigate and we couldn't (even if I were skilled in reversing) use the car to help, so it is invaluable for us and we can then park within an inch of a wall. For us, its the best thing (after the 'van) that we have bought.
Hope this helps.