Genesee,
I am building a 2.56" bodytube, 37 inch long zipperless rocket using Stu Barrett's design. From the motor tube to the coupler bulkhead is 7 inches. I've installed the baffle in the bodytube above the motor tube like the ROL diagram shows. The baffle is mounted 3 inches above the motor tube. The ejection gasses should be cooled enough after making a few detours around the baffle then through a series of holes drilled in the bulkhead so as not to burn your chute. Kinda depends on how long your motor tube is going to be. I've read somewhere that the distance should be a minimum of 5 inches. Hope this helps.