@Hallroadfarm 

I remember seeing a very detailed answer before, oh, this, which may help you:

https://community.tp-link.com/en/business/forum/topic/530760?replyId=1046164

  @Hallroadfarm 

Meshing requires the controller.

  @Hallroadfarm 

You can also just rotate the EAP225's antennas so that the planes (imagine a sheet of flat paper passing through the centres of each antenna rod) of each pair of antennae face each other, the body of the AP doesn't matter.   Also make sure the antennae are 90' apart (V-shaped)...so 45' downtilt from vertical each, and NOT parallell to each other!

I have a similar situation and distance.  -84dBm is on the cusp of being useful and in my case I lose another few dBm when it's raining (I don't have 100% clear path..there are a few tree trunks in the space between APs.  On my second reposition iteration, I mounted one AP high under an eave that has a wire mesh screen behind which afforded me some apparent 'gain' and improved my link quality by 1-2dBm over what it had been higher up mounted on a pole.