Based on the information you've provided I'd say your best chance of success is to put the longer cooking piece of meat in first, then wait the appropriate amount of time and put the other piece of meat in so that they both finish together.
The Ham takes approximately 3 hours a whole turkey takes 5-6 hours. I typically cook them a 225 degrees. I usually put the ham in 2 hrs after I put the turkey in and this has worked well. What I'm trying to do now is cook a Ham and just Turkey Breasts. I'm wondering if anyone has cooked just Turkey Breast and about how long it takes.