Taken from my conversation with my shaper (and husband) Jon Wegener...
I know you've been wanting a shorter board, and you are going to need a smaller board for steeper drops and hollower waves, and I've been thinking about a board that my brother Tom handed down to me. It was a Rick Surfboard shaped by Phil Becker...I kind of based it off that a little bit. That was a great board, me and about half my friends learned to surf on that board.
The nose of your board is semi-full...I wanted to keep it kind of full to help with your paddling. The width is carried farther back into the hips to keep it volumous. But then the board has a bump winger on the tail to use as a pivot point. You tend to surf from the middle of the board so that long straight rail will let you turn from the middle of the board like you do on your longboard, but the bump wing will act as a pivot point so that when you do learn to step back and turn with your back foot you will be able to do a tighter turn. It will loosen it up and make the board feel like a short board.
Why a single-fin? Your surfing lends itself to a single-fin...single-fins generate speed by moving up the board, and by trimming...not from doing roller coaster etc.
Tom told me I couldn't get a new board until I tube-rode that old Rick. (Do you think Jon was trying to give me a hint with that comment???-r)
Now, most of you will never have a shaper that knows you as intimately as my shaper knows me;) but the idea is still valid. If the person that makes your boards knows you and how you surf, and you give them the creative freedom to make you what you need, not just the board you want...you will be a better surfer for it.