We have been involved in many imports, mostly MH's but recently trailers are becoming popular.
Your main worries will be using these trailers on the roads. I may be able to help here. Electric Brakes are the main stumbling block. Recently there has been a lot of to-ing and fro-ing, between new owners and VOSA/DVLA etc., so they are becoming aware of the limitations of the classic trailer, and as such road-side checks are now common. There is nothing wrong with the electric brake, but remember that only the vehicle fitted with the actuator can tow the trailer. It is such a grey area that it is now better to conform than "buck" the trend. - Thatís where it gets costly.
You either modify the brakes to take a cable, change the axle or go the whole hog and re-chassis, which is the best way because then there is a chance to re-balance the trailer so to come within the majority of tow vehicles hitch weights. You also gain the convenience of corner steadies and a proper park brake.
I have a contact in the States who can do this - probably cheaper than here,
On importation, you may already know that you pay duty on the value (sale price) plus shipping costs. The duty rate depends very much on the size. Then you add VAT to the total. When shipping consider if you REALLY want to keep the roof AC this side of the Ďpondí as this bumps up the price somewhat, so do awnings. The shipper often re-measures the trailers and will take the extreme measurements, which includes all the outside bits. Some owners even remove the awning and put it inside - but remember the shippers are no fools, check first and donít forget the brackets on the side.
It sounds petty, but it can make the difference of a $1000 or so.
I am not far from Southampton and can offer services - including all electrics, road and domestic, and a small camp site.
Don't take life so seriously.... it is not permanent!