https://www.amazon.com/dp/B07R5NFBVL?psc=1&ref=ppx_yo2ov_dt_b_product_details

I bought this bag, and with OhNoItsGetzz's idea to saddle it under the seat, I found something that's really effective. The only issue I found was that it rests back a little farther than I'd like. The reason being is the back screws of the seat get blocked by the bag. So I have to position the bag back and they almost clip the tire, but so far have not.