RF modulation band. collision problem (2.4Ghz)

I'm using a WiFi module now it's 2.4Ghz and I also need to have another RF modulation device on the same pcb to communicate with some other devices, So because of the WiFI modules 2.4Ghz modulation I can't use a 2.4Ghz modulated RF device so I have shortlisted a 900Mhz RF module (FHSS modulation).

So I want any suggestions and guidelines on what precautions I should take in order to develop a pcb that's performing well with all that disturbance.(Given both the 2.4Ghz and 900Mhz modules would be on the same PCB but on the opposite sides)

shortlisted module >> HumDTâ„¢ Series RF Transceiver Module - Linx Technologies

WiFi chip ESP8266 or RN171