Please don't construe anything I write here as advice, just to add to the discussion. I'm only giving you the advice I got over the years that I was adventuring. A good bit of it was as a caver and a good bit of it was for situations underground where keeping your kit to a minimum was essential if not existential. I also backpacked and canoed for 30 years before age caught up with me.
1) Forget suturing. If it's that deep, your big worry is sepsis.
2) Tourniquet? Expect to lose the limb if it is that bad and you're that far out. Use pressure wherever possible
3) "Fortunately the vast majority of first aid needs, not involving serious thoracic or abdominal trauma, can usually be addressed with kit on hand. A shredded shirt as bandage, magazines or branches as splints, foil or plastic wrap (sandwich baggie) to seal a sucking chest wound." -- This. +1
4) Buddies get out. Loners end up as mulch.
5) Staying warm and dry is always Job 1. Hypothermia is always a possibility. Carry a large plastic leaf bag and some plumbers candles and learn how to use them. I've seen this save lives above ground as well as below.
6) Shock kills. Apply your emergency blanket before you need it.
7) If there is any injury or malady that gets you asking: "Should I keep going?" It is already becoming too late. Get out.
That is excellent advice.
Sutures: I do not even attempt sutures on livestock. I call a vet. But steri-strips are a staple at the house and in the field.
Emergency treatment of shock is something that many fail to adequately prepare for. Blankets, plastic sheeting, and fire starters are of paramount need when serious injury presents.
A horse accident separated a couple of my short ribs in the wilderness. It was Fourth of July in beautiful warm conditions. But I got knocked into an icy cold stream and soaked.
Fortunately we were horse packing, instead of back packing, and we were carrying about 400 lb of supplies. Lots of room there to include emergency items.
Bottom line, the cold and pain made me shocky as hell. I had lots of dry clothes and a good sleeping bag available to crawl into while the teenage boys made camp and cooked dinner.
The only thing I might add to this discussion is that there is a time for self rescue, and there is a time for sending your companion out to call in an air ambulance. It is important to recognize the difference.
