I will be hunting elk in New Mexico Unit 2, I expect to hike a bunch, I will be using an MOA Evolution with a Nightforce NXS 3-15 scope. I'm looking for a relatively light pack that will hold the rifle, a hydration bladder, jacket, rain gear and that's it. I will be hunting all day and any help or suggestions would be greatly appreciated. I've looked at the Eberlestock packs and they look great but they seem to be on the heavy side. Thanks.

Pick any pack you want. There are plenty of threads on this forum with pack reviews. Add a Kifaru gun bearer to your selection. The problem with a day pack is that your first load of meat out is too light and it is a wasted trip. I use a Kifaru Freighter frame with a Pack Duffel. After the hike in and camp is made I cinch down the pack bag and hunt. There is also thread about the pros and cons of day packs and large packs.

I used a KUIU 3200 Icon Pro last year. It will haul a full quarter with ease. My only complaint was loud zippers.

It is a pretty good day pack.

Pick whichever day pack you like. I have a couple of different packs that I like and use regularly. I have a Crooked Horn Gun Commander that I quickly swap between each pack and it works perfect for my needs and provides quick access to your rifle. Probably just me, but I had a Kifaru Gun Bearer set up on my Kifaru Longhunter pack, and could never get use to barrel of my gun in or near my forward field of view.

I use a Badlands 2200 and "gunslinger corral" and like the combo.

If I were buying again I'd think seriously about the Horn Hunter Main Beam pack.

I'd also look at some of the higher end packs like Kifaru, Mystery Ranch, Seek Outside etc.

Not near the top end stuff some of you are using but I wanted something similar and landed on an Eberlestock F1 Mainframe F1, Superspike duffel, scoped rifle scabbard, and padded accessory bag. Like you said it isn't lightweight but I've carried some heavy loads and it does well. It is like a .30-06; does everything well enough but I'm sure there are a lot of things out there that'll do specific things better.

Not a fan of gun scabbards in bear country.

Take a look at the Alps Pursuit pack.

Hpg umlindi with prairie belt and kifaru gunbearer. Adjustment of the latter takes a bit of effort for good muzzle control if more than one other person around.
Add a pocket or dry sack if you need more space.

Kifaru gun bearer with any pack....

If you just want a light daypack and you like Eberlestock, you might look at the X1A2. It's a lot lighter than my MR packs and has a wide scabbard made for heavier rifles with bipods and larger objective scopes. The scabbard on the Just One is a bit tight for my setups. If you're hunting elk, it's not like you are going to pack it out in one load anyway, so you'd be going back to camp/truck for a full size heavy load pack anyway.

Midway has them on sale now for $155 if you need extra incentive.

Kuiu Ultra 1800 is perfect for day packs and the gun holder on the side works much better than hanging off the back like the badlands 2200 which i owned and sold. Check em out if you haven't and you can get a good discount if your a first time buyer....

I use a Mystery Ranch Bighorn for my day pack and have no problem hauling a quarter out for that first trip.