Add X-Forwarded-For to Proxy HTTP protocol

Hi,

I have an f5 cluster in front of a squid proxy cluster, and I want my squids to get the X-Forwarded-For header, which is not the case today.

My definition is as follows

ltm virtual /internal/webproxylb {
    destination /internal/10.1.1.80:3128
    ip-protocol tcp
    mask 255.255.255.255
    pool /internal/squidproxies
    profiles {
        /Common/fastL4 { }
    }
    source 0.0.0.0/0
    source-address-translation {
        type automap
    }
    translate-address enabled
    translate-port enabled
    vlans {
        /internal/vlan5
    }
    vlans-enabled
}

I understand that as long as I am using FastL4 I cannot add X-Forwarded-For, but if I do try to remove it (I suspect it has been added to enhance performance, so I'll have to take some care), will I be able to add X-Forwarded-For? That is, will the F5 recognize the

GET http://whatever.com/path HTTP/1.1
Host: whatever.com

as an HTTP request that it can add an X-Forwarded-For header to without changing anything else at all? All the examples I have found seem to relate to reverse proxying where the protocol is the plain

GET /path HTTP/1.1
Host: whatever.com