I pretty much hunt elk exclusively in a backpack/spike camp manner. Hunting from the truck tends to involve 4 hours or less of sleep and thousands of feet of daily climbing. Backpack hunting usually involves 8+ hours of sleep and 30 minutes of climbing each morning. Being close and tight to where the elk are has many advantages, but you really need a well dialed in, ultralight, super compact and easy system or it’s not going to be very fun.
I use a 6x9 8oz tarp + 5.5oz bivy sack + 18 oz quilt. Minimal weight, minimal bulk, stupid easy to set up and versatile. If I don’t need the tarp, I don’t set it up. Hammock setups are also super appropriate here and extremely versatile, but have a steep learning curve and can be a bit of a money pit.
Limit you backpack profile to no wider or taller than your body. Since you’ll be hauling more gear around than a day hunt and since you are often off trail in the dense timber, you need a tight profile else you’ll get snagged on everything.
If logistics allow, stage food so that you can further cut weight and bulk and potentially stay out longer.
Know the comfortable limits of your gear and sleep system, don’t try out untested gear on hunts. *Do multiple weekend backpacking trips (or scouting trips) to get your gear and system dialed in. Test your sleep system in the backyard if you have to. You need to know what’s comfortable, what works and what doesn’t. Every night you spend out will allow you to get a little more comfortable and build mental database for dealing with various conditions.
If you skip the test backpacking trips, you will most certainly fail at this venture. In order to be an effective backpack hunter, you must first master ultralight backpacking concepts. You don’t master anything with 1 or 2 nights out. Hunting will be heavier, harder and probably colder than most backpacking. If you aren’t going to follow through and do multiple overnight trips out, don’t bother trying because it’s not going to work out for you. You won’t even know if you like it until you do it.