I've been following this thread and must say that I've run into a similar problem with the Thomas Duplex and Ilford Warmtone paper using Rosco 19 Fire & even adding some layers of a Rosco Red. MGIV is fine, just the WT (FB in my case). I also have two of the Kodak "beehive" style lamps with Kodak OC filters & 15w bulbs - this setup is clean up to 20 minutes - I got bored after that. I wasn't ready to use the WT paper & with the OC filters that's about as far as I went.
Keep up the good work.