Thankfully I didn't have to design that - I'm not that smart -, all I had to do was shuffle parts around for a couple of weeks until I converted it from double sided to single sided. Oddly enough my single ended up smaller than the original double. 
That's only V1, my final one with added circuits and stuff is even more complicated.
This is what I meant about stretching FZ to the limit, because when I tried to ground plane it I couldn't get some of the contacts thermal isolators to stick. Some stuck, some just wouldn't, so I gave up on ground plane.