thanks for the advice guys but i always use mind over matter. i don't mind and you don't matter. :-D
seriously though it's possible, you just have to use your imagination as long as the gross train is within limits and the trailer is under 3.5 ton then you are ok, how you go about that is up to you, i removed the engine armour, batteries and anything else that was easily removeable and put it in the towing vehicle and it towed fine. we might have been over, we might have been under, i didn't go on a weigh bridge so can't say for sure but it felt good to me.
how anyone else does it is their concern but you could buy a 4t daf and chuck it on the back, insurance for me was £130 and 19mpg makes for a good alternative .
rick