I wouldn't call it "creative", but if you can maintain the proper pitch (check local codes) towards the existing pipe, I suggest digging a ditch and burying a PVC 4" hard line. Cut it into the existing line just past the existing cleanout with a directional sanitary 'T' fitting. At the "working" end, just use a 90° fitting with a stub up to a standard 4" screw cap cleanout at ground level. I dug a hole around mine and filled it with crushed stone, so any minor spillage when unhooking the slinky can drain down instead of puddling.