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Does anyone have a Holtey?

You don't need a 2-axis angle finder.

Take a dowel, put it on your miter saw, put a 10 degree angle on it. Now put it on your stool and mess around with the splay until TLAR (That Looks About...

I have the same plans from benchcrafted. I don't see an issue with the dimensions you give. Have at it.
Where'd you get the thick mesquite? Or are you laminating?

I've found that anything I store vertically invariably ends up bowed, bent, or crooked. Your mileage may vary of course, but I don't do it.