You're possibly looking for the Coupé top, which is available here: https://shop.pimoroni.com/products/pibow-modification-layers
You drop a few layers from your PiBow, stick the Coupé top on, and can plug add-ons right onto the GPIO.
The alternative is to route something like Black HAT Hack3r out of the case: https://shop.pimoroni.com/products/black-hat-hacker
You can either go out through the side by snipping a portion of the case away, or through a Coupé top.
I've been known to get a bit... uh... creative... with my pin breakouts:
