What's the story on that bizarre undercarriage?
I think the clue is in the caption to the first photo in post #4:
Ground effect testing on Otter 3674 in 1957. Tufting installed to show airflow, fully deployed batwing flaps and engine running to blow flight surfaces.
The purpose of the rig is presumably to get the desired clearance between the wing and the ground. It's not clear whether the rig is intended to be towed, or whether it's just the prop that's providing the airflow to energise the lifting surfaces.
Either way, it clearly isn't expected to leave the ground trailing all that ironmongery.
