Mobile Hotspot Repeater?

I have a complicated setup I need help with. I have tried this before and failed. Now I need it set up. Here is a picture of the setup I'm needing (I have all the hardware)

I remember trying something with a repeater function but I didn't route it to a new wifi connection, I believe I only bridged it to ethernet.

Mobile Hotspot (internet)

WIFI1 (192.168.X.0/24)
ssid - network1

OpenWRT (router)

WIFI2
connected to network1
IP : 192.168.X.150

WIFI3 (192.168.0.0/24)
ssid - network2

Device1

connected to network2
ip : 192.168.0.2
internet routed from WIFI2 which is connected to network1

Device2

connected to network2
ip : 192.168.0.3
internet routed from WIFI2 which is connected to network1

Device3

connected to eth1
ip : 192.168.0.4
internet routed from WIFI2 which is connected to network1

The reason I am needing this is because I have a home surveillance system that needs a constant wifi connection. My mobile hotspot is my only source of wifi and there are no ISPs where I live so using a dedicated wifi router would be useless. I need my internet provided to my devices when I am home, but when I am not home I need them to still be connected to the same wifi network. Any help would be greatly appreciated.