The length is not the deciding factor, the flexibility of the limbs is the deciding factor. Finger pinch can be overcome in various ways.
Like Pat said, the length should be no shorter than 2x draw length, for a bendy handle self bow. This a good rule of thumb for the average bowyer. That would mean 56" for 28" draw. If you add a 6" unbending portion for the handle and fades, then that would translate to a 62" bow. But it looks like you know that already.
I've seen a 28" draw on a 48" bendy handle bow... in The Traditional Bowyer's Bible. It was nearly 3" wide, if I remember correctly.