what does the rifle or rifles you want to shoot weigh? and budget ?
I've got a gitzo 1720 head personally, just waiting on the gun to be built to see how it does, I think its capacity is around 8.8lbs, if you add the hogsaddle and rifle I will be real close if not over, but I had the same idea primarily run a spotter but also use the saddle for shooting
a buddy of mine runs a 055 manfrotto ball head on a manforotto tripod for his hog saddle but he is primarily shooting off his with 15-17lb rifles in comps but loves the set up