Features and Implementation Status
1. All Backpacks Changed - Implemented
Ultralight Backpacks have 2 slots and weigh 0.5 (Special Backpacks are buffed)
Small Backpacks have 4 slots and weigh 1 (Special Backpacks are buffed)
Normal/Medium Backpacks have 6 slots and weigh 2 (Special Backpacks are buffed)
Large Backpacks have 7 slots and weigh 3 (Special Backpacks are buffed)
Extra Large/Hiking Backpacks have 8 slots and weigh 4 (Special Backpacks are buffed)
2. Change to Starter Backpacks and availability of Backpacks (Loot Changes) - Implemented
3. Reduce amount of available backpacks on all maps and make larger ones rarer and worth more influence - PLANNING

Note: The idea was to make backpacks make more sense and be more "realistic" which meant decreasing slots and weight. I also wanted the backpacks to be used more often, a lot of this will come later with Loot changes, but I have rarely ever used a 6 or 7 slot backpack in all my time in SOD2. As soon as I find an 8 slot I use it, screw the consequences. I intend to make it so you really have to work up to 8 slots backpacks so that all these great assets get used more.

Side Note: Unfortunately you can't have more than 8 slot backpacks which is why I made all characters start with 4 pockets in the CSO mod.