Thanks for the replies.
In no particular order...
I don't have a tow bar fitted yet. The car was an ex staff car, (4 weeks old) when I bought it, and as part of 'the deal' when I bought it I negotiated a towbar and electrics at a discounted price. I've just had a call to say its now in the garage so the Tarraco is going in for it all fitting next week.
The Milenco mirrors rely on the clamp fitting on the wing mirror housing, and the problem is that the glass of the mirror fits the housing so well I cant get the leg of the clamp in the gap. I don't want to force fir it in case I damage the housing.
I have looked at fitting the mirrors onto the bottom of the housing, but there is a lip on the underside which I think must be to keep muck from getting onto the side camera lens.
I'll keep looking for a solution..