Failover for load-balanced WAN ports on SRX5308

Hi all,

we are currently seeking for a new multi WAN router solution and the SRX5308 seems to fit to our needs, but I'm not quite sure if it is able to fulfill our business continuouity needs. Here's our scenario:

We have two 100Mbps VDSL linesm one with a static IP and one with a dynamic IP and both connected via fritzboxes 7430 to the provider. All traffic should be load-balanced between the two connections, specific rules need to be applied for certain destination IPs and ports to be routed to the one connection with the static IP.

Additionally we have a LTE backup connection with static IP via a LTE modem. During normal operation no traffic should be routed to the LTE connection, only in the case of both VDSL lines are down everything needs to be routed to this third line (also for the destinations we originally defined for the static IP WAN).

Is this configuration possible with the SRC5308? From the data sheet is seems that either load balancing over all WAN ports or simple failover is possible.

Thanks for a feedback in advance,

joerga