The problem is the drip pan being too close to the charcoal holder. Aluminum is a very good heat conductor so it will get very hot. Oily drippings will start to smoke profusely and it will impart a nasty taste on the food. A bigger issue is that the oily drippings can catch on fire especially since there's no inside lip on the drip pan. Oily drippings will drain adjacent to the charcoal holder increasing the likelihood of catching on fire. You need at least 1/2" gap between the drip pan and charcoal holder. Also stainless works better since it's a much poorer heat conductor in comparison to aluminum.
Even with a 1" gap between the drip pan and charcoal holder, it still gets hot enough for oily drippings to smoke.
Drip pan is filled with ash to act like a kitty litter. Ash absorbs the oily drippings and prevent it from smoking during high heat cook. Makes clean up easier also. I just dump it every couple times i cook oily meats and replace with new ash.
If you want a drip pan for your 26 with lips on both the inside and outside perimeters, a 22" convex comal will fit perfectly. Just cut out the center portion.