They don't really need a full 6-man rotation, they just need to give him the traditional fifth-starter treatment. Skip his turn now and then when an off-day keeps the rest of the starters on schedule, give Leake and Lecure a spot start once a month, etc. That would bring Chapman in at 28-30 starts instead of 35-36. That should be sufficient, I'd think.
Not all who wander are lost