Believe me, next time I will rout the channel while the top is still flat! I have learned my lesson. But with that little fixture I found it to be so much more controllable moving the guitar under the fixed router instead of the other way around. Like an inverted router table. I think I might even consider making a more finished and stable version in the future. But for now, scrap particle board and a 2X4 did the trick. I know the resulting channel looked a little ragged but the fine side of a 4-in-one file smoothed it right up. And since I was sanding back down to the flat anyway, I didn't even necessarily need to do that.
I will say that I only had one desklamp on and it was clear across the room so I was practically in the dark. But it really accentuates the shadows and I could tell immediately where my high/low spots were. Anyway, just a tip.
As for a wet pic of the carve, I will bust out the mineral spirits tonight. Expect a pic tomorrow.