Think about grafting....
My Grandfather was a genius at grafting fruit trees, and I don't suppose nut trees are that different. He would graft the trees so there would be four kinds of apples, plums, cherries, peaches/nectarines on each tree...so with four trees he had 16 different fruits. Even as a kid I thought that was cool. I was only about 7 years old when he showed me how to do it, but while I always wanted to try it, I never have done it yet.