Normally I don't season the sausages for my fatties I just go for bold or Italian, sweet whatever to go along with the insides.
If you do add seasoning and want the flavors to really come through I would use a more mildly flavored sausage and add it in at least a few hours before and let it set so the flavors can meld with the meat.
I'm with Herky, go with the ground pork and season yourself. I did justthat for my Chili Relleno's Fattie and I may never go back to Sausage as teh flavor of the meat was great. ( Ok I'll use some sausage again, but I don't have to with seasoning my own as the flavor was that good)