hmmm echo many of the sentiments on here so far .... buy second hand and save the money for early retirement
there are many helpful generous people on here who share their experiences.... opportunites for parking up, even in a stealth camper, are limited for any length of time and living on the road in this country is a difficult option really now
I juggled a camper and the boat for a while, but was too much of a ball ache in the end, and the camper was standing idle .... but if you have a permanant mooring and a job then that is different ....
also see the thread i started on "continuous cruising with a vehicle" for one way of carrying a motorsickle ..... despite the predictions of some, i have not sunk (yet ) and have a safety certificate, and tis easy to get on and off without knackering my back. I find the bike very useful for blatting around to shops etc .... just moor near a bridge and away you go....pushing it along the towpath of course
I will be near selby in october and happily have a chatter with you about my limited experiences of living aboard so far .... 9 months .... love it .... and you can moor up pretty much anywhere without hassle, town, village, rural ... wherever .... and after some years living on the road, the space is great