Does anyone have ideas about a possible battery placement on this board?

Basically title.

Because I live in Paris, it would be nice to buy batteries in store. The most promising model I found is a 180mAh 32x17x4mm lipo.

I could also theoretically use one of these li-ion cylindrical batteries, but they are longer than the keyboard's size (which is 77mm).

Here's what I already tried:

• removing the inner thumb key, which makes the keyboard 34-key and leaves enough space for the battery mentioned above. Though after a few hours of using home row mods on my current keyboard I don't think that will be a good solution.
• moving the MCU (Seeed XIAO BLE) to the right, which makes the board 2cm wider (and doesn't look very good since I have no keys there). This one isn't very elegant, plus I don't really want to make the board wider, and I'd like to avoid it even though it is a solution.

Please ignore the mounting holes and TRRS jacks, I am still unsure about whether or not I want to just ditch bluetooth and make this board wired (which works with kmk)

The ergogen config is available on the github repo.