Before starting to form the rough profile on the plates, I had to get them down to the right overall thickness. Again, I thought of doing it manually, but the bottom plate in particular was quite thick - about 25mm. I like working with maple, but I don't like it so much as to remove 10 mm evenly all over a large piece of wood! So I ran both top and bottom plates through the thickness planer. It worked amazingly well. There was no tearing out of grain even at the fragile corners, and the finish is very smooth.
After renewing the edge thickness lines, I clamped the top plate between dogs on the workbench and started removing material with a medium gouge. As long as I was careful not to cut into downward-running grain, it went very well. As usual, sharpness is key.
I got the lower bout of the top plate pretty much roughed out. I'll have to "hone my honing skills" before moving on to the maple bottom. Sharpening hand tools is still prone to random results, but I'm sure that by the end of this instrument I'll be much more consistent.