The cans nest inside each other, the tarp can wrap around the roll of bags so it only takes up about as much space as an oatmeal container.
The hobo stove is made from two cans but they fit inside each other, which fits in the paint can. The other soup cans could be laid on their sides end to end in the bottom, or side by side. Those can lay in the bottom of the tool bag and still have a good amount of room. The roll of trash bags is mostly used so it's pretty thin at this point which takes up even less space. Water bottle is on the exterior, so it takes no space. Not to mention the external pockets.pouches. I'd say she's used maybe half the space in the bag, especially since she's not toting around a change of clothes, shoes, or anything like that. You could also lay the paint can on the bottom on its side with the hobo stove in it, with the tarp folded up and stuffed on edge into the can, laid along the bottom of the bag like padding or a liner, or leave the tarp folded up and on the exterior side pouch. There's a lot of possible configurations to the bag. 

Fallen and I have talked a lot about this character over the last week or two, and I've helped her with gear and even loot generation. I need to look at the bio and stuff more on my end.