For proper Mesh support you need a triple band device with two 5Ghz radios + one 2.4GHz radio. In this case one 5Ghz radio is dedicated for wireless backhaul traffic, while the other 5Ghz radio provides the connection to your devices (together with the 2.4GHz radio)
See this post for an overview of triple band devices.
Regarding other questions like practicalities or what has to be taken into account, I don't have the answer (I don't own such devices myself)