Some really good comments and suggestions !
The LT4000 was confirmed at a painful £1195, though there is another model on its way (the 'compact') at £975. Still rather OTT methinks when considering other much cheaper alternatives suggested here, and depreciation from new could be an issue should I buy a boat needing a different trailer anytime soon.
I'll enquire the dimensions of the bike trailer though. If the wheels aren't too far forward then could be OK with the weighty o/b mounted. Maybe a project for next year
So back to the good ol' box trailer. I anticipate a couple of custom locking castor boards and a wall chain should safely position it in the garage on its side and preserve space. We had a little Erde ourselves some years back, but would get something larger for the big tent and boat.
Does anyone transport their o/b mounted on the back of a box trailer (obviously with an anti-theft security bar)? I ask this as the Tohatsu 4s is over 50kg.