I would take exactly the same things on a 2-3 night trip as for a 5-7 night trip except for the amount of food. Since all my food is commercial freeze dried, protein bars and snacks, the food doesn't add much volume. Neither does my kitchen, which is nothing more than a JetBoil stove, an insulated drinking mug, and a spork or spoon.
I've used essentially the same packing system for 30 years for solo trips: one Duluth pack with waterproof liner, one small waterproof backpack as a day bag, and more recently a heavy but comfortable bag chair. I used to carry no chair at all.
I don't have a real good picture of my packs, but you can see the green Duluth pack on the ground, the small roll-top day pack in front of it, and my bag chair under my hat. My three person tent is in its own waterproof stuff sack under the top flap of the Duluth. All my food is in an Ursack inside the Duluth. My 10x12 silnylon tarp and a bag full of ropes is in one pocket of my Duluth along with my folding saw, and my gravity water filter is inside the other pocket of my Duluth.
Here is a camp set up on the same trip. The tent it a three person Losi with both a factory fitted ground sheet and inside sheet. My gravity filter is set up on the tree. The Ursack with all my food for seven days is tied lower on the same tree. At night, I would tie the Ursack to a tree about 50 yards away from my tent. My packs go in the tent at night. I rarely use the tarp because, perhaps luckily, I usually just catch short showers and use my rain gear or sit in my big tent.
To lighten my load I'd get rid of the chair and could bring a smaller tent. With a hammock rig, you could fit that and a small fold-up chair like a Helinox inside a big pack easily. If I wanted to go out for two weeks, I still wouldn't take any different gear except to add more food. That would probably involve buying another Ursack. I like sacks and packs because, unlike barrels, they are light and collapse in volume as you use your food.
To calculate my pack volume (which I've never done before), my #3 Duluth Cruiser is 95 liters (5800 cubic inches):
My Seattle Sports day pack is 29.5 liters (1800 cubic inches), cost me $32 on sale at REI, and looks very similar to this later model version:
So, not counting my big chair, I can fit everything I need for two days or two weeks in 120 liters (7600 cubic inches) of packs.
I don't paddle any more in cold weather, but if I did and needed more room to take bulkier clothing, I might need to take a larger second pack instead of my Seattle Sports day pack, possibly my 76 liter (4650 cubic inches) GoLite Gust pack with a waterproof liner inside:
You don't really have to spend a lot of money if you're just going to trip occasionally. I see people in the Adirondacks carrying everything in garbage bags.