As you say many larger M/homes tow a car, but I suspect the majority of your M/home observations(like mine) are based on overseas long term trips in the winter, where the usual M/homers are generally well off pensioners, whereas the majority of M/homes are probably on average smaller coachbuilds, vw vans and the like, used mainly in the summer for weekends and the 3 week annual hols. 5ers therefore may be considered as an option for the first group but not for the second.
You state the 5ers advantages, but the vast majority stick with the conventional ubiquitous "single unit" in its various guises... why?
I may be wrong {and often am) but I can't see many 65+ people taking up the 5er alternative, the proof is out there.
I hope your reason for late leaving to the winter sun is good one, it means a lot to you getting on the road I know. Myself, I get ready and think of going about week before the actual off. Which is why I usually forget something.
There's still a big chunk of the Brit summer to go yet!