Short Stack is suiting my purposes well, but I've decided to rev the board to bring the cost down a bit (the lipoly charger and power path have much more configurability and control than needed). I'm also looking at using the SAM L21 which would cut runtime current in nearly half (theoretically). The L21 also adds a few interesting features (op amps). I'll also max out the flash as things get really tight if you want to, say, use both FAT on the microSD and another heavy stack like BLE (There's plenty of room if you use the SD raw without a file system). Additionally, I want to source different FETs (decrease footprint, lower on resistance, lower leakage) and inductors (better availability).
After I verify the next revision, I could release all of the design files and libraries if folks are interested. I'm also open to making boards to order.