@Xbit 

Hello.  Are you using the EAP's meshing ability?  I have done a number of outdoor 'area coverage' solutions using the EAP225-outdoor, which can be spaced at least 200' apart as long as they have clear line of site.  The advantage of the meshed outdoor APs is that they are standalone units that provide local wifi coverage and wireless backhaul of that traffic.  Typically I wouldn't recommend going more than about 3 wireless hops, so

Your ISP HQ==WiredAP - - - - - - 1st Wireless AP - - - - - - 2nd Wireless AP - - - - - - 3rd Wireless AP

That expands your coverage by say 200' x 3, plus maybe another 100' in local wifi coverage off the 3rd AP...so up to 700' away.  Note that the wireless backhaul is done on the 5.8G radio.

Beyond that you will want to use wireless point-point bridges, like the CPE710 or more recently the Omada manageable EAP215BRG pair to go to a point 1500' away and create a new WiredAP site there.

If you have an aerial map of the site/area with scale, we can perhaps make more accurate recommendations.