I wouldn't be fixating on the Colregs. Single handing on overnight trips is a violation of the basic principal of a continuous watch. The issue in this case is whether you believe that your radar watch guard setting and alarm is going to i)actually spot a target; and ii) you'll awake.
I think it was Capta (and others) have pointed-out that there are situations (shipping lanes, hazard areas with fixed objects, weather shifts, etc. that conflict with the need to rest to some extents have to be balance to reduce risk. Without getting into variable issues, i) you need to know what your capabilities are, ii) you need to not go into situations where you really have used-up your reserves, and iii) you need to configure your boat's sail plan and equipment to minimize the likelihood of a real problem.
Lying a hull isn't such a terrible strategy sometimes in certain seaways, heaving to sometimes might work, and maybe (in the right circumstances) just reducing sail and depending on autopilot or steering vane probably would work many other times. All of those are dependent of your (lack of bad) luck and the what, where, and how.
It's pointless to argue about prudence, compliance with regulations, etc. -- it's really about the notions that those things don't matter more than ones freedom to just do it. Of course there are situations where that really isn't just your personal decision that might impact someone else.