@ScottHardin you should really post this in the Wireless LAN forum but in answer to your question, all Meraki APs support mesh and it does just work. However a wireless only AP can, as far as I know, only mesh with a wired wireless AP. So in your case AP1 and AP2 would work, but AP3 would look for AP1 rather than AP2.
Also remember that ever wireless hop halves the data rate so AP3 would be a quarter of AP1 speed if it were able to work.
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