Got it finished, but won't be winning any beauty contests. It was so cold the caulking tape wasn't cooperating, I'll clean it up with a putty knife whenever spring gets here.

A keen eye might notice the receptacle itself is not "straight" ... that is correct, it's rotated a bit on purpose. I bought a fancy weather tight 90-deg pigtail adapter that goes from twist-lock to RV style 30-amp, and it was manufactured a bit off-kilter for some reason. So, I aligned the receptacle so the 90 deg cord could hang straight down, rather than off to the side. The cord I'm using now is the 25 footer that came with the RV, with a new end on it.