Interesting topic ! I was looking on how to have SUP supports that could fold easily to be stored in a small place.
My solution:
- buy a pair of basic wooden trestles
- fill the hole by placing a wooden plank in it, screw it in place through the trestle top and sides. no need to perfectly fit, some gap is not an issue
- saw out a slot, wider at the edges. easiest way is to drill a hole at the bottom with a bell saw and cut through plank an trestle top
- cover with bits of pad.
Voila! Easy, cheap, folds like a normal trestle, and the added weight of the plank stabilizes them.




Note: the half plastic bottles on bamboos are to drive away moles... They rattle in the wind and make the moles believe some predator is walking by. Or so my wife tells me :-)
Note #2: the board is a 2017 7'5" Gong Fatal, with a "sci-fi" tail & channel, quite an interesting design on the water for extra squirt and water release in turns - Disclaimer: I a am a Gong ambassador.