Traffic Routing with out a Snat ?

I agree with hoolio. You need to change the default gateway of the nodes to the floating IP on the F5 and turn off SNAT. That will allow you nodes to see the client IP. However, once you do that you may not be able to manage the nodes. You will have to setup a virtual forwarder to forward all other traffic sourced from those nodes or else the F5 will not pass it. Let me know if you need more info on the virtual forwarder. You will probably need it if the node VLAN is not isolated behind the F5.