We have a TomTom Camper & Caravan and can't really fault it both in solo and towing mode.
It has diverted us round some pretty serious tailbacks just recently both towing and solo.
It updates the maps on virtually a daily basis via Comunity Content.
The only "fault" with it is sometimes it takes you on a circuitous route,for instance from our house there is quite a direct way to the M1 but it sometimes takes you on a route I personally would never use.
Apart from that,excellent.
There are free lifetime maps at present :-
http://www.celstores.com/
Ian