Cisco FTD / FMC 4G backup link auto failover, L2L tunnels to consider.

Hey! We're looking to add a 4G backup solution to our FTD 1010 (Managed by FMC).

So what I want to achieve is that once the primary WAN link goes down, it should automatically switch to the 4G link.

Some considerations are that we have four L2L tunnels to different sites, and they also need to come back up once the fail over is done. I guess you can configure that in the tunnel config, that the tunnel always should originate from this end, and in the other end the adress should be dynamic?

Any idea how I would do this in FTD / FMC?