Which pack should I get?

1. – if you’re concerned about the mesh pockets, go for the Southwest with solid Dyneema pockets
2.  The 3400 weighs virtually the same and would give you a bit more room and versatility.

I’ve found the Osprey EXOS 58 an excellent UL pack and the most comfortable of that type I’ve ever used.

Last fall I even used it for hunting with 40 lbs. of gear including butchering stuff PLUS a 9.5 lb. scoped .300 Win. mag rifle.

It carried well and the rifle was strapped vertically on the right side, butt stock sitting in a Kifaru “Gunbearer” Hypalon belt mounted pouch, the barrel held vertically to my right shoulder with the Kifaru Velcro & webbing strap with a QR buckle. This rifle cary was necessary for me to be able to use my walking poles.

The Arc Blast is a fine pack but has an external frame.  Good if heat is a concern (excellent in fact) but it will take the load a bit away from the back so, like all external frames, a load can feel off momentarily with sudden movements (especially loaded with water).  Brings back the old external vs internal frame arguments.  If balance is a concern (cross country, iffy trails, etc..) look at the HMG but if cruising on a major trail in summer, the Arc Blast.  Of course the Arc is adjustable…. I’m getting another one in spine resistant fabric for summer.

The 2400 is pretty tiny. It’s a small 2400. After you give the roll top the necessary 2 folds there almost nothing left to use an extension collar if needed.

Based on your gearlist, you could probably do it but you’d need to stay weight/volume ruthless and not head out for too long.