IMO yes, too heavy for back country. I had a 13 lb rifle just for stand hunting, walking no more than 1-1.5 miles in, mostly 1/2 mile hikes each way. I did NOT enjoy that rifle, and I am a pretty big guy... 6'3", 210 lbs. It was a tack driver, but unnecessarily burdensome. Sold it. For myself, I find the happy spot in the 8-9 lb range, loaded and with optics. Not too heavy but not so light accuracy becomes a challenge.
I'd say that's too heavy for backcountry. I've hunted with rifles ranging between 7lbs and 20lbs (AIAT I used for treestand hunting was a behemoth). I personally wouldn't want to haul around anything over 10lbs.
A rifle over 9# is too heavy for me.
For Backcountry I prefer 7.5-8.5# Rifle all up.
Recently moving to Shorter Barrel & mid weight optics keeping weight in the middle.
Makes for a pretty Manageable stable setup,
My 280ai is 10.5 scoped and loaded with a bipod. That’s about where I would draw the line. After I shot my buck at a whopping 90 yards this year I wished I had brought my sub 6 lb Kimber instead...
Only you can decide if the rifle is too heavy. What is light to one person may be heavy to another.
I personally will not take a heavy (to me) rifle on any hunt that I will ever do. 8 pounds all in (minus the bipod) is my sweet spot no matter the terrain.
If you will be hiking hard and expect offhand or shots without a solid rest...a super lightweight rig can really bounce around on you when your huffing hard. I have rifles that are sub 7lb scoped and hard to hold steady freehand. Agree on 8.5lb all up is about perfect.
The only back country experience I have is in Kodiak. My heaviest rig was just shy of 9 pounds all-up. I was in the prime of my life then, and that's all I wanted to deal with. Going from that to a rig just over 7.5 seemed to make a big difference in my comfort.