Not to literally "keep my head up" but to balance out front-to-back trim, I've experimented with putting a few wraps of heavy fleece around my biceps under my drysuit, between base and thermal undergarments. Essentially the same effect as wearing a thicker undergarment top, but more targeted, lift closer to the head than all over the torso.
Since the fleece is inside the drysuit at ambient pressure and not closed cell like neoprene or a pool noodle, the lift is consistent regardless of depth. It actually worked pretty well, might play around a little more with that idea this season. About 45"x6" of heavy eddie bauer fleece around each bicep affected trim nearly the same as a pound of lead in each drysuit thigh pocket, or 3 pounds of tank tailweight, or very heavy negative fins. The fleece increases lift though, instead of increasing weight, and meant for slight less gas in the wing, and seemed like precise finning was a little less effort with less mass to kick around.