What benefit do you want to get from spinning it? A rotisserie is usually used to help something cook more evenly like a whole chicken, where a side gets heated directly and then it has time to cook/transfer heat to the inside before it gets another wave of direct heat, repeat until deliciously done. With low and slow indirect cooking there usually isn't one side exposed to much higher heat than the other. If you have that problem, I would try deflectors first. That said, I know several BBQ joints like to do ribs in large rotisserie setups where the dripping fat auto bastes the next rack as they keep rotating from top to bottom. I have never tried to spin a brisket or even thought about, but I am curious to hear your thoughts on why and hear about the results if you try it.