How are you routing traffic to the devices? Are you using a routed segment between the external VLAN and whatever is in front of them (firewall?) and routing the VS subnet to the floating IPs or will the device/firewall use ARP?
If ARP I think this should work. I can't quite decide if you need MAC Masquerade or not but its probably a good idea.
If L3 routing you'll need dedicated routes for the VS's associated with each TG. So any you'll need to route any VS IPs in TG1 to the TG1/F_A floating IP and and any in TG2 to the TG2/F_B floating IP.
Am I making sense?