...it would be uncomfortable to carry it folded and slung across my back because it folds to the left, meaning either the stock or charging handle will dig into my back.
+1
My last folder came from Combat Stocks and I actually miss it now that it's gone. The hinge would lock solidly in place, and it folded on the
right. Folding to the left would be awkward to fold or extend; you'd have to move the weapon out and away from your body, or rotate it 90 degrees to give it clearance. Then there's the matter of how your hand needs to be positioned to make the change.
I see no good reasons for a left side fold.