MPLS for failover internet connection

[Chris_Harvey]

FTG60c running v5.0 fw

WAN1 is connected to the local ISP's modem, another carriers MPLS router interface is connected into a switch behind Interface1 at the main office. On the other end of the MPLS connection is another FTG60c in a datacenter with a 50 meg internet connection. Currently I can route traffic between locations fine but I would like to know how I can have the main offices internet failover through the MPLS connection. This looks feasible with v5.2 using virtual wan but I do not have that functionality with v5.0, any input would be appreciated.

Main Office

FTG60c WAN1 (1.1.1.1)

             INT1  (192.168.100.254)

Static Route 192.168.200.0/24 192.168.100.253 (MPLS RTR)

Data Center

FTG60c WAN1 (2.2.2.1)

             INT1  (192.168.200.254)

Static Route 192.168.100.0/24 192.168.200.253 (MPLS RTR)