Trailer mirror position help?

[KINDMARE]

I am putting a mirror in my trailer to help settle my horse whilst travelling. He has one in his stable and seems to find it comforting.
The trouble is, where to position it - the best location is at the front but can horses not see straight in front of them???
Where have you got yours positioned?

 

[Flowerofthefen]

Friend positioned hers on the inside of the top door over the front ramp.