Regarding the caravan why don't you just go round to their house, tell them you need the space to work on your landy, give them a story about a potentially big repair you might need to do.
Then park it up, lift the bonnet and put a big piece of mechanical looking oily something or other next to it.
Leave it there for a few days tinkering on it.
Or, just go and ask if they could please move it, I understand being a neighbour, and wanting to keep some sort of civility it might be benificial to have some sort of 'excuse'.