IP Source Routing

I have two autonomous BigIP boxes on two different subnets. Each is deployed in a one-armed configuration where the pool members exist on the same subnet as the BigIP… the servers use the BigIP as their default gateway and pool members for each virtual server can exist on both subnets so to ensure traffic is routed back through the BigIP that received the connection I am SNATting the incoming source address. The problem is with streaming video… I can’t stream unsolicited UDP traffic to a SNAT address so is there a way through iRules that I can inject source routing into the IP packet to make sure it comes back through the BigIP that started the connection? If this is possible I can then maintain the client IP but the return traffic will not, necessarily, go to the servers default gateway. Any help is greatly appreciated.