I need some ethernet cables between my computer room and the TV room. The
easiest way is to run the cable in the crawlspace and then up through the
floor for about 1 foot.

The plan is to drill a hole from the crawlspace up into the space between
two inside walls (one of them is the TV room) and between two studs. Then I
can make an opening on the wall for the faceplate and the network jack.
There is an electrical outlet on that wall, but I don't think that's going
to help.

If I could drill the hole from the top between the walls and between studs,
that would be easy. But since I can't get a drill inside the walls, I have
to drill up from the crawlspace. How do you identy the area between two
drywall, from the crawlspace looking up?