News Exterior Transfer Switch Location and Clearance
I think your location may have more than 1 issue. 
Normally the maximum height is 6-1/2’. The door on the transfer switch must be able to be opened to 90 Degrees.
The space in front of the opening usually requires 36”. These requirements are in the NEC 110.26(a)(1), 110.26.2 &amp; 110.26.3.