I don't have an answer for you on your pole placement, you need to determine the LOS from each dish and make sure you won't be pointing into the back of any of the others when they turn to track the arc I guess. I have seen dishes pretty closely spaced at cable headends, but those dishes are fixed.
This may not be of use to you but I discovered you can enter lat/long coordinates (in lieu of street addresses) into the Satellite Dish Angle Pointer on Sadoun's site. By doing that, and taking the coordinates to 4-5 places to the right of the decimal point (ex. 37.7654, -93.13526), you can locate the pointer
EXACTLY at your dish location(s). Once you have that you can estimate very closely what your LOS will be if you can estimate the height of your obstructions. Hope this helps you out and good luck!