There's quite a few posts on various forums regarding the Yeti and Milenco mirrors, most say they do fit with clamps close together. Even on my Insignia they do fit but the fitting can be fiddly.
The Skoda Yeti door mirrors have quite a rounded curve on the top but the bottom although slightly curved are much straighter which the Milenco towing mirrors can be clamped to. However, because the towing mirrors will be upside down you may have to change the left to the right and vice versa so the round bar rises upwards instead of downwards. Just make sure that the the two thumbscrew at the front are unscrewed to allow any twist on the curve and that they are set at their furthest point to avoid any vibration. Once the towing mirrors are set into position, tighten the front thumbscrews to permanently set to the shape of the door mirror housing then tighten the other two thumbscrews to the door mirror as normal.
As pointed out the Milenco mirror arms & clamps can be dismantled & swapped about any way you like. The mirrors can be clamped on top or bottom edge of mirror housing. If put on bottom edge though you might find when mirrors are folded the clamps hit the bodywork which might cause damage if knocked in.
If you play around with them long enough you should find a way of fitting them that works. My experience anyway. Otherwise try the Maypole large strap on mirrors designed for taller mirrors. They will vibrate more than Milenco but will do the job if you cannot make the Milencos work for you.
I've given up with the Milenco mirrors on my new Berlingo. They are not really secure enough. The edges of the mirror housings seem too steeply angled. I've used them this summer & they ain't fallen off but they can be pulled off quite easily. Previous Berl had different shape mirrors & the Milencos fitted ok.
So I got a pair of Maypole large strap on mirrors & they go on ok. Go Outdoors have them on offer £20 for a pair.
So if anybody in the Colchester/Clacton area wants a pair of perfect condition Milenco clamp on mirrors in their zip bag £30 please indicate or I will ebay them next March.