I understand what your up against, Painted my first car outside Tuesday in Alabama, not by choice we started at 6:00am and really I was shocked how clean it turned out.
Your right a single stage would have been a better choice.
I would forget the $260 a gallon Delstar and call or email Larry at the web site below.
He has a paint company that makes specialized paint for aviation, boats and trucks. They have a Polyurethane the red is under a $100 a gallon and is some good looking stuff.
Larry deals with your problems everyday with the boat manufacturers as they are to big to pull inside a booth so he will know the best set up for you.
He has other paint lines and may recommend another line for what your doing, I don't know.
I'm thinking he could get you epoxy, primer and paint for $200-225 when done.