What camera do I buy? / general gear talk

Here's my initial ideas for a custom bag based on Bigxtop's daysack: https://www.bigxtop.com/collections/bags/products/daysack

Along the front there'll be two waterproof zippers, like so

This will give me top access like a standard bag when needed, and if I lay the bag flat down and open both zippers, I'll have access to something like this

(though opened from the front)

Have to run it past Jordan, but the idea is to have a fully removable insert so I can pull it out and get a regular rucksack.

Would love some input on this. Feel free to shoot it down, not precious about my ideas, just want the bag to be as good as possible