Did you look at 210.52(F)ex2? What does the AHJ think about it?
Correct me if I am wrong bit I do not know of an article that would require a separate circuit for the furnace igniter although you still need one for the air handler if this is not the same as the AC. (we don't have a lot of <any?> furnaces here)
As a design issue I would have 2 circuits for general lighting, just so you are not stumbling around in the dark when you trip the breaker. You can pick up your "other kitchen loads" and the smokes on them.
I agree the SABC rule seems silly here but rulz iz rulz. I don't know of a loophole. The handbook shows a picture of picking up the fridge, disposal, "dining area" receptacles and range igniter on the SABCs so that helps your load diversity.
