My bobcat 763 has hand controls for driving and foot for loader. Seems like with the Z turn mowers out there that have joy stick controls, you could modify one from a two handle to a joy stick. Or what about something like the cub cadet zero turns that use a steering wheel. Or how about a rod...
Consider buying a thumb for one of the buckets. It is almost like having a grapple. I personally think it gives you the best of both worlds. A bucket when thumb is open and a grapple when operated.