That's what I did. i.e. no extra diffuser in my mini. I also left the tamale strainer in and made sure the holes were not lined up with those drilled in the pot. Cooked 3-4 pork butts with no issues.
Smokemaster Offset*'70 Hasty Bake*WSM 18.5*'00 Plum SSP*'69 Cado*'90 Red MT*'73 WSJ*Imperial Kamado