The way to avoid a “valley” around carving is to gradually relieve the wood as you get closer to the design. You might have to go back a good inch or more from the carving, if you have the room. The important thing to remember is to keep the the the area where the wood is removed as gradual and as consistent as possible, to “feather” it out from the design. If you don’t have a lot of room, such as near the butt piece, just keep the angle of relieved wood consistent. Not sure if all that makes sense…, here’s a quick drawing that might explain it a little better. Also, an example of a design behind the cheek piece. No “extra” wood anywhere in the area, just “feathered” out wood removal. Hope that makes it a little more clear.
Also, don’t be all that concerned with stabbing too deep. To me, it’s desirable to have an “outline” along the edge of your carving design. In fact, if I don’t outline my carving with a very small “v” gauge, I usually re-stab around the design to create an outline. Stain will appear a little darker in the re-stabbed area, creating an outline, which accentuates the carving.
Best,
Ed