Wow, that sounds like a bad idea. I could very well be wrong, but if the pig gets done before the chicken stuffed inside it, you will either have to overcook the pig, or undercook the chickens. Undercooking the chickens could lead to a whole lot of time in the bathroom, if you know what I mean.
Add the fact that this will be your first cook on a new cooker, and I see all kinds of potentially bad things happening. You are asking for ideas to season your new UDS, so you can do a first cook of a pig stuffed with chickens?
Help me out here, brethren, am I the only one just a little bit worried?
I may be a complete wuss, but I would go a little less out there for my first cook on a new cooker.