First things First
In re: the taking a bearing in a bouncing small vessel.
You don''t have to get an exact compass reading to do a safety check. If you can line up two fixed items on your boat(e.g. a shroud and a winch) onto the lights so you have three marks in a row, you can very easily take a "bearing" without digging out the compass. Try to line up the three items again in a couple of minutes (Shroud, winch, light). If you can do it again, think about starting evasive maneuvers.
Somebody jump all over me if I''m wrong here, but this is how I generally check withgout a handbearing compass handy.