Hello Gerk,
I know, it's an old thread...but did you found a solution ? I encounter the same problem (RP => IIS => redirection) and can't find a way to make it work correctly...
Thanks for your help/reply.
Here's my config (in case of... :-) )
FMS 11 on a single Windows Server 2008 with IIS
Apache Reverse Proxy on RHEL 6.5..