Hi Mark,
Yes I will be around that weight, maybe a shade lighter but in that ball park. Bearing in mind that my FL2 is an automatic, I was averaging around 22-25 but in strong headwinds drops to around 19-20. Regarding the difference between towing a single axle to a twin; I find the twin more stable particularly in windy conditions, having said that my previous van always towed very well without any significant issues. I used to tow around 1400Kg and obviously the performance was slightly better than it is now, acceleration wise. I didn't have any problem with any site, except on some sites the pitch size was to small and we had to pitch diagonally, or the access was very tight with to many obstructions in the way. However we are pleased we made the change, love the extra space and not having to make the bed up every night etc...