I haven't seen this posted anywhere on the forum regarding provisions. It may be against the balance behind the idea.
In addition to the current way to get provisions, why can't a noble buy provisions like paraphernalia? A region lord could set aside x bushels to be sent to the market to be purchased as provisions. The conversion from bushels to provisions would depend on unit size.
I didn't post this as a feature request because I wanted to get some input on it first.
Two things I believe, the current system was somewhat easier to do so it was just made with the intention of working on it more later, like the not starving at the same level as the region instantly when you run out of provisions that was done. Secondly, I am not sure on this but Tom might not be doing for game balance reasons but I am not sure, I just thought I read it somewhere.