I-rule to re-direct page back to source IP address?!

Well, technically, with an iRule couldn't you write whatever you want into a header named...whatever you want? (X-forwarded-for included)

I'm not saying the other systems would know what the heck to do with it, but I would think you could get there:

when HTTP_REQUEST {
  HTTP::header insert X-Forwarded-For [IP::local_addr]
}

You might need to use header replace instead if it's already getting put in somewhere else along the line.

Colin