I use a Speed Graphic, Grafmatic film holder, and my iPhone as a light meter when I need to go light. I can fit all of that, plus a dark cloth, loupe, notebook, and a couple of spare lenses and filters in my Amazon Basics camera backpack. It's the size of a regular school backpack. If I want to take more with me, I have a separate Amazon Basics over-the-shoulder camera bag that carries about 5 lenses and lens boards, plus several other tools. The Grafmatic film holder allows me to carry six sheets of film in the space of one and a half film holders. The Speed Graphic is great because not only does it fold up fairly compact, but it's well protected when it is folded up, so you don't have to baby it. And while the light meter apps have their flaws, if you get used to using them, you can figure out how to work around their weak points.
My point is, if you're going to make longer hikes with this gear, I don't think the best answer is in the best backpack. Rather, if you can find ways to lighten your load, then you don't need as big of a backpack. Also, I find it easier to carry multiple packs rather than one big one. It makes organizing easier and allows you to distribute the weight more evenly around your body. Plus, it's easier to locate stuff, and cut back on gear that you don't need when going on longer hikes without having to repack everything.