Hi @mackworth,

Most likely, yes, this should work.  Though you may have an RF "shadow" in the bottom right-hand corner of your yellow oval due to obstruction of the signal by the smaller portion of the house.  Given your mounting height V-formation will probably be best.  But you could also try each antenna mounted completely horizontally.  One antenna should point towards the back yard, and one towards the side year.  Note that the shape of the signal is roughly a toroid (donut) whose hole is aligned with the central (long axis) of each antenna.  Such that of the antenna was vertical (like a pencil standing on end), the donut would sit flat on the table.

Will the EAP225-OD be ethernet connected (ideally) or MESH?  Do you have any other EAP225 or 245's already?  I have 2xEAP225V3 (Ethernet) and 2xEAP225-OD (MESH) and an OC-200.  My outdoor units are MESH connected to one of my 225 indoor units.  

It took me a while to arrive at the optimal placement for my initial outdoor unit.  I have a two-story deck attached to the house.  I first mounted the AP about 9 feet up on one of the wooded 4x4's.  This was more or less centered in my back yard (left to right).  I expected it would provide good coverage for the back yard.  But it did not.  I tried with the antennas vertical and in a V-formation.  I think the main issue was that it was too close to my indoor AP.

I finally moved my AP to my outer perimeter fence (hence the MESH) and mounted it ~5 feet high.  I tested multiple antenna configurations but V-formation.  This arrangement provides very good 5.8GHz (and 2.4GHz which I don't use) coverage for my back yard which is roughly 100' wide by ~50 feet deep.  My house is a rectangle in the center of a 1/4 acre plot.  Additionally, I get some coverage on either side of the house.  But not "in front" of the house as it blocks the RF.  So I put an additional MESH attached unit in the front yard.

Due to the MESH hops I only get ~100-150 Mbit/sec from the 5.8GHz link (I have gigabit FIOS) but other than that it works great.

-Jonathan