I would like to know more about the charcoal "liner" and how intakes are setup. Pics of the intakes, exhaust, and fire basket design, along with a description of how the fire is lit and maintained would help.
I agree that a lot of fat burning in the fire can be problematic, and even I started using a pizza pan wrapped in foil as a diffuser to keep the massive flow of liquid fat out of my fire in the UDS when cooking multiple butts. When those hunks of meat start giving it up cooking at high heat, it's almost like a thunder storm. They can really pour.
Modded Brinkmann Gourmet. Basic UDS. Rescued 22.5" OTS. SJS Mini-WSM. Stubbs. B&B Oak Lump.
Cannondale 2009 F8 (for burning off all the great BBQ)