You could use a Win32 API call to hide the VI's window. It won't bother the web server, but it will get it off of your server's screen. I can't remember where to find the Win32 library online, but I've got one that I like to use. I can send it if you drop me an email.
There may be a more elegent way to do what you want, but the RFP functions are rather rigid about having the host VI's panel open.
Daniel L. Press
PrimeTest Corp.
www.primetest.com
dan.press@primetest.com