I put a piece of flat bar in there and bolted up some 4 point harness's. I didn't like it . It was difficult the reach the dashboard and the upper mount really needs to be below shoulder level. I took them out and put the stock belts back in.
Installed a set of ProArmor's in mine a couple years ago, same thing, took them out and put the stockers back in. Retractable's might work, otherwise it's too restricting and too busy in that little cab area IMO.