Balancing a 20# bird on a rotisserie, especially if you haven't used it before is a Thanksgiving Jackass movie moment waiting to happen! But, I digress, I'd either spatchcock it or set it upright on a Foster's can. Good luck.
Southern Brethren BBQ Competition Team
"It's all about getting paid!" - Myron Mixon
"I love being hated in my hometown!" - David Hair
KingFisher Gator Rotisserie cooker, WSM, Stainless 5 burner with IR gas grill, Turkey Fryer, Weber JD Commemorative grill, slightly used Bandera chamber for future use as a cold smoker, Masterbuilt 40" insulated ELECTRIC smoker