I've done it a few times and posted about it here once....of course this was back in the 'old' h2o days so of course I got a lecture.

In a driftboat that is set up properly, with a confident, experienced captain and filed float plan (someone should know when and where to expect you when you are done) all controllable safety aspects are covered.

Go for it.

On select summer nights on the upper hoh I've been known to take a solo moonlight float...well, I've done it three times anyway.

I look at it like solo hiking or flying. Cover all possible safety aspects except the hand of god and do it.