Good Morning!
Thank you for your message. You are right about the tight fit with the corbin saddle. We do sometimes work with customers to customize racks, but usually only when it's something we can make production when there is enough demand.
We have model MWL-630-FLAT (
Indian Chieftain, Roadmaster, & Springfield Luggage Rack - FLAT) which is specifically made to fit the Chieftan, but we don't know the seat configuration to be able to tell you for sure if it will fit. If you can send us pictures of your bike and maybe even measurements, we can possibly give you a better answer as to whether or not it might fit.
Thanks again,
Bernadette - Motherwell Products