If I was going to try to smoke something that small, I'd probably only smoke it for 90 minutes or so, and then wrap it in foil with some broth and slow cook it at 225 until it hits 190 or so - and then if I wanted it to be tender, I'd probably turn down the heat to 170-180 and leave it to continue breaking down for another couple of hours.

Cooking just the flat - and a small one at that - makes getting it tender and not dry really hard.