So, I've decided to try and fit everything in board with minimal soldering. With an OTG adapter and wifi dongle attached my Zeros will come in at a whopping 65×53! My leaves measure 115x60. Yeesh! Maybe some micro-surgery will recover 1-2 mm clearance from the dongle. All I know is, I used up around 25% Of my filament just getting my rails as they are now!

That fence is nice to have, but if I flip the Zero over, move the hole up and make allowances for the protruding minihdmi and microusb connectors, lateral fitment won't be an issue anymore. But I won't be able to keep the fence. And I'll be forced to implement some kind of peg mounting system...