All, I have done the installation and it is working like a charm now. Thanks to all who helped guide me by providing useful information.
So that this might help others here is what I did that worked, AND what did not:
The setup is in an old Mid Century Modern wood frame house by a famous architect. I could not cut into the walls and all wiring had to be hidden. Also, just to complicate things further, the tenant in the home could not know I was working on it. Initially, I had cable brought in to the basement so I connected a router, firewall, and switch there. The router also had a wifi and VPN capability with some add ons. I started with 1 wifi camera in a breezeway only 30+ feet away. All worked when set up in testing elsewhere. However, the wifi was not configurable to adjust power levels and could not connect with a strong enough signal to get through 2 wood walls and reliably connect to the camera.
NoloC suggested Powerline so I ordered a TPlink AV2000 kit (returnable) as well as two Ubiquity Nanostation LocoM2s (suggested by TomasLTU and Copex). The TP link were reviewed most highly in various places. The LocoM2s were chosen because the 2.4 ghz freq is supposedly better at blasting through things (vs M5).
The Powerline did not work at all. Even testing on two adjacent outlets on the same circuit. I suspect older code had different setups and Powerline is optimized for some new setup. I know the house is properly grounded and all good 12 gauge solid copper.
I set up the two Locos in wireless bridge mode so one is off the switch connected to the router and is aimed at the outbuilding. I have the power turned up all the way to 23 db in both Locos. In the outbuilding I have the other set up in the same way and paired to the first. It is actually 10' further than the first camera and through a third wall (but no insulation or sheetrock on the inside).The remote Loco is hard wired to a switch in a utility closet in the outbuilding with POE and two other cameras are also hardwired to the switch (outside I was able to route wires without drilling/cutting/defacing). The switches are current Netgear 100mbps port switches.
The Ubiquity setup has some non-intuitive configuration but their tec support was diligent (though I DID get differing answers on separate calls so had to be persistent) but was overall pretty straightforward and the pairing was cool. Encryption was easy.
Anyway, I am watching the house now
and all is good. I hope this thread helps someone else...
Thanks again!