Wow, Richard, I've wondered how that Gehl round baler would work behind a smaller tractor. That's the only baler I've used personally and if I remember right, the manual recommended a minimum of 50 hp. And the only tractors I've used with it have been an 85hp Oliver and a 120hp Deere. We usually just made 5' x 5' bales, although occasionally 5' x 6'; Johnson Grass, rye grass, coastal, and haygrazer.
Bird