I have 2 new boards and need to put rail tape on them so was looking in the garage to see how I could support the SUP on it's rail so I could apply the rail tape.
My solution was to make a minor mod to my Bunning's saw horses.
(New $17 but I got 4 of off Gumtree ages ago for $20 and sold the 2 I didn't need for $20 ).
Finished product 
Off set the bases otherwise it'd fall over 
Just relocated one leg up against the other and tighten all the nuts and the uprights(legs) stay where you put them. 
Need to rest a piece of wood across to stop the bottom rail touching the bolts then I have a couple of pieces of marine carpet to protect the board. 
Counter sink the new holes (same as the existing holes) so when upside down it doesn't rock and sits flat
Just threw this last photo in of the standard wall mount solution, still waiting for a verge collection to pick up some pool noodles to go over the dowels.
Select to expand quotemike3217 said..
just do what i do make the wife hold the board
Or if wife (or kids) unavailable just stand astride the board and hold it between knees.
Yeah I have put rail tape on successfully before using wife /kids/knees but also wanted something to hold the sup while repairing a rail. For some reason the family don't like holding the board while I'm sanding 
Select to expand quotetightlines said..
Will a 14'er fit on those wall racks?
You know you want one.
Ha I knew you'd ask that and yes it will fit at the top, just need to move the top kite and put a support there and then it can poke out above the other shelving. I have extra holes for a forth position so can drop the other boards down one place if/when that time comes.
I put the rail tape on both boards today and it was so much easier and I also put RSPro traction grip on the nose to the 9' surfer.
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.
Made a dedicated side on support - do enough rail stuff to justify it.
Narrow board slot for surf sups, wide board slot for bigger boards.
Padded the top so it doubles as a normal board support when not in sideways use.
Lots of duct tape required.
Disclaimer - no one in their right mind would pay me to promote their products.
