Just use one size bag and take things out then?
To be honest I always think that the stuff you need on a bike is the same whether out for 2 or 6 hours, and, as I’ve said IMHO, most people carry loads of stuff they don’t need.
Most first aid kits are junk, there is nothing important in them that some duct tape and a clean hankie can’t deal with ( I’ve been a nurse for 20 odd years so my view may be different to others).
Cameras need special bags anyway so they are available to actually use without stopping and faffing.
Food… unless you are taking a whole chicken, you should be able to stick food in pockets or in your small bag.
Coats get stuck in pockets or on the back of the small bag.
I’m obviously different to you, but I think the less you carry, the more fun you have.