Trust me I have looked longingly at that Horizon plate with the graduated holes. It's a thing of simple and elegant engineering beauty. :)
I use lump charcoal. Start with a full chimney of lump to start and pour that in a circle of lump I placed in the firebox, somewhat Minion like. Depending on length of smoke, I will add extra pieces of lump on top of already burning. I want to buy/build charcoal basket so I can place hot chimney of coals on top of basket of unlit coals. Seems like this will let fire burn for quite a bit longer. I actually have the opposite problem where I have a hard time keeping under 250 and would have an easy time keeping at 275. Once my fire is going I actually close the damper on the firebox and have the chimney in the smoker closed half way. Seems to work in our climate.I have this smoker and so far it is very nice. My only problem is getting the temp high enough. I can run 220 or 225 but can't get higher then that with out opening the ash pan. I made a sheet metal baffle but I need to remake. seems like a cookie sheet would work out well as those pictured. I made a charcoal basket and even only putting hot coals in it seems the fire chokes out. How are you running yours to get that hot, Lovinspoonful? Are you burning wood or charcoal?