Thanks for the encouragement

On the other hand, my arms are sore from sanding all day. How do you prevent sanding through around the edges? That was the most difficult part, especially sharp edges, like around the perimeter of the headstock.
Despite the finish challenges, the bass actually plays fairly well. It appears I did an ok job on the frets, no sticky outie frets ends, and there's only one note that buzzes, the "A" string, on the 9th fret. Which is weird since I was most concerned about the slight relief on one side and reverse relief on the other in that area. The middle was actually fine. I'll have to take a closer look at that tomorrow. The neck didn't blow out when I tweaked the truss rods, so that's another plus. I know that neck is likely too thin. Feels great though. I also may have to make a new nut - I think the g string is a bit too close to the edge of the fretboard.
The pickups sound pretty good, but the output is pretty low. I never made any setup for height adjustment - I was too focused on putting the thing together, but they could be closer to the strings, which may fix the low output issue. Additionally, the G string is noticeably lower output than the other strings. Perhaps the height adjustment will fix that. or a better spaced nut. We'll see. It could also be that I used the bridge pickup for the neck position and visa versa - I never marked which was which when I put them in the covers. Right now, I have a flat metal plate across the bottom of the poles, with neo magnets just stuck to the metal. I may have to put the neo magnets directly on the poles. (I didn't ever magnetize them) I still haven't shielded the control cavity or pickup cavities and the bass is noisy - until I set both pickup outputs the same - then the noise totally goes away. I reverse wound one of them, and put the magnets reverse to each other on each pickup - humbucker style, which apparently is working.
And finally, while most of the finish is nice and glossy - and I'm real pleased with that - the orange color is, well, not exactly my taste. I'm still deciding what to do about that.
This is definitely a learning experience, and I learned quite a bit on this one. Thanks to everyone for all the help and encouragement. I'm already thinking about what I'll do for my next build, now that I know I can build functional necks.
Oh, and as an afterthought, I'm impressed with the varathane clear coat, despite my learning curve. It fully cured overnight, and is less stinky than nitro. Just keep it in a cool place...