Could I carry all my gear in a 40L pack?

A 2P DCF shelter sounds bulky.

I’m guessing you have a WI Blazer bear can from the listed weight. That’s a moderately large can.

I’m guessing you will not comfortably fit all of that into a 40 liter pack although everyone measures their pack volumes differently. That sounds like a pretty full ULA Circuit to me (I see your other thread) which is much larger than any 40 liter pack I have ever carried. I think the Circuit sounds like a reasonable choice. I haven’t used a Waymark so I cannot speak to that.

You can try to find a box that has 40 liters of capacity and see how that goes. Also you could take all your gear to REI and try stuffing it all into a pack or two.

Unsolicited derail: Most of your First Aid and Personal Care sounds like a lot of weight (and therefore bulk). Repackaging your sunscreen, for example, would save nearly a half-pound. There are other places you can save some weight (and again, bulk) if you want to talk about those.

The bear can, teapot, chair (and probably the bladder) are all bulky. You might be able to fit the can if you dropped the other items, but definitely not everything on that list.

A 40L pack can take a lot internally/back mesh pocket, some even a BV500 with decent enough circumference, but a 2P shelter would likely push it.