Charles, I'm with you all the way. Just trying to control the variables I can control - it's nice to have a plan with no huge flaws at some point in the process (and the beginning is always a good spot for that), just so you can see how far away from it the final product comes out to be...
I'm also a rank beginner at both Sketchup and woodworking, so paranoia about pretty much everything seems to be the fallback position. 😲