For getting out of the cockpit quickly, you want the escape hatches certified as part of a mod. for package carrying that filled the fuselage aft of the cockpit bulkhead. Given the engine locations, if you go out the underside just before the wing, you should clear everything (the engine intkets being over the wing or close enough that you won't get swept up). Still, I could see a "tunnel" to such a below the engines drop hatch that would leave most of the fuselage tanking intact; it wouldn't be spacious, but it could work. I suspect you might need rollers on the floor to slide down it.