Bowed strings do not have the same requirements as plucked strings as far as their bracing plans are concerned.

Modern arched top violins have no need of bracing but they used to make tenor and bass viol da gambas with flat tops and this is one of the bracing plans used in the renaissance and early baroque except my photo shows the bracing as dotted lines bleeding through from the drawing on the back.

Therefore, the vertical brace is actually on the opposite side as the soundpost which normally would go on the right behind the bridge. (Not that early gambas had a sound post, but for a winebox cello or hardware store panel topped bowed string instrument of some kind, a soundpost will probably help the volume).

Just move the vertical brace to the left side and voila: A simple bowed string bracing scheme for a flat top bowed string instrument.

Modern classical guitars are starting to used arched backs to focus the sound. One of the things they did before arched backs was bentwood backs which also helps focus the sound and much easier to pull off with wall paneling.

Do a search on the internet for bentwood gamba backs if you're interested. You'll eventually find it.