Nice Topic!
Just my 2 cents (well actually $ 3.60): here a nice small ESP2866 "proto" board if you want to create an ESP8266 + RFM95 node. Anyone cares to create an RFM95 adapter plate for it? (probably I should call it "base plate"?)
A very minimal description is found over here. and some more: [1], [2], [3], [4]
Oh and by the way: the result will not be CE certified