ISSPRO has just released a blank filler plug (I couldn't believe we didn't already have one). Can't remember the part number, but we just started shipping them to OEM customers. You can call 800.888.8065, ask for Aftermarket, and ask them about it. If they don't know the part number, have them call Georgina in Engineering. It's brand new so it might not be in the system yet, but I know we have them!
Regards,
Michael Pliska