You can turn any bag with a loop backing into a custom, fully function, medical backpack with many of the same functionality of a purpose built pack. This video shows you some of the options out there for stand alone medical organizers that will allow you to make whatever you need, in whatever form factor you want.
Vertx Insert (Code PrepMed): https://vertx.com/overflowmeshpouch...
Tasmanian Tiger Inserts: https://tasmaniantigerusa.com/range.p...
Mystery Ranch Insert: https://www.mysteryranch.com/removabl...
Vanquest Gear Inserts: https://www.vanquest.com/products/lb0...
Vertx bag (Code PrepMed): https://vertx.com/basecamp
Hill People Gear: https://hillpeoplegear.com/Products/C...
5.11 AMP: https://www.511tactical.com/amp