Well, I've spoken to my dad since and asked him some questions about it and this is what he had to say.
I asked him if he had ever had to reverse and he said no, it's not possible. If he ever got into a spot where he needed to reverse he'd unhitch the boat, reverse and turn the caravan and car and then hitch the boat on again.
I also asked about the legality of it and he said that yes, it was perfectly legal. He said that with really heavy loads you would need a braking system but that because the boat was an inflatable it was very light so the whole train was fine.
Then at the end of the conversation he amended that to say he assumed it was legal because he towed it here, there and everywhere in the country and was never pulled over!
So that's the towing train info right from the horse's mouth ;)
