Yea I've been searching for one that has some extra storage capacity. Dont need a travel bag but need definitely something that can carry an extra shirt or two, hat, sunglasses, some snacks, etc.

This a relatively cheap, quality looking one I found Vibrelli Hydration Pack & 2L Hydration Bladder - High Flow Bite Valve Hydration Backpack with Anti-Microbial Technology https://www.amazon.com/dp/B01LLO83WA/ref=cm_sw_r_cp_apa_i_KgbfBbWZAG4RR

https://www.amazon.com/dp/B01LLO83WA/ref=cm_sw_r_cp_apa_AGBzBb25DEEA4

Is this comparable in size? I dont want to take something and then be told it's not allowed in.