Don't try to solve all of your problems in advance. Make yourself available for your opportunities. If you try to envision the entire guitar and every little step along the way, the project will seem impossible, too complicated, beyond your ability, and just plain too risky to even start.
Make a drawing. Make a template. Cut some rough blanks to size. Buy a truss rod. Anything! Just take that first step to break out of this willy nilly mode. Once you begin the project, everything will become clear and take focus. Just take it in small pieces.
If you're not familiar with doing your own set-ups on your guitars, it would be a big advantage to learn that now. This will help you in untold ways during the build process and of course finally getting your new guitar to play and sound right.
It's not that hard if you go slowly, take one step at a time and keep your focus by not getting ahead of yourself.
We look forward to great things from you even on your first attempt!