First, the answer depends on the purpose of your trip
At one end of the spectrum trips involve a little walking and a lot of camping. At the other end you are walking from dawn to dusk and spend little time in your shelter other than to sleep. The best balance between weight on the trail and in-camp comfort will depend on the purpose of your trip.
For long walks, excessive weight affects your comfort and safety too
If your trip is more at the walking end of the spectrum, you should be prioritising comfort on the trail rather than comfort in camp. And nothing destroys the pleasure of walking faster than excessive weight, particularly in mountain country. Excessive weight affects your safety too - fatigue makes you significantly more prone to error, accident and injury.
So the assumption of your question that a heavier pack will provide greater safety and comfort doesn't really hold.
For 3 season alpine walking, I'm safe & comfortable with a max base-weight of 5 kilos/11 lbs
This is a reasonable target for exposed alpine thru-hiking without making significant sacrifices in comfort or safety. At this weight I can be safe in a major storm and comfortable down to around -5c/20f. This weight includes:
- A very comfortable and ergonomic rucksack
- A rugged phone with GPS
- A GPS Personal Location Beacon
- A small tablet for reading and backup mapping
- A 6000mAh battery for recharging between trail towns
- A high-end travel camera
- An MP3 player
- A very powerful torch for off-trail night walking and a spare for camp
- Warm, dry clothing for camp and sleeping
- A warm, full-sized sleeping mat
- An ergonomic sleeping pillow
- Full rainwear
- Full cooking gear
- Full bug-protection.
As you can see, I'm hardly cutting corners. This is the max I would need for three seasons - for shorter, warmer or more clement trips I would shave a fair bit off this base-weight.
So what am I sacrificing in terms of comfort and safety?
Very little, in my experience, and the lighter weight makes walking much more enjoyable. The more ambitious projects on my bucket list simply wouldn't be practical with a heavy pack, so lightweight gear opens up (quite literally) a world of possibilities.
The main sacrifice is tent-space - it's sized for sleeping. Though I have plenty space to cook, pump up my sleeping mat and pack my sack under cover.
More generally, you have to spend time and $$$ to achieve these weights. You have to treat lightweight gear with a bit more care. And you have to budget to replace it more often.
To get much below these weights you have to start cutting corners and relying on skill and hardiness to get you through. For me, this is the happy medium.
So how do you achieve these weights?
As anyone will tell you, you start with the Big 3 - your tent, pack and sleeping setup. A full discussion would literally fill a book, but modern materials mean that each of these should come in at under a kilo / 2 lbs.
Some general tips:
Shelter: you can save a lot of weight by using walking poles for the support - stronger than tent poles and weight-free if you're a pole user. By the way, use full-weight aluminium poles and you need have no fears about stream crossings. They won't weigh any more than your staff and have a myriad of uses (but that's another discussion). Vendors like TarpTent, TrekkerTent, Yama, MLD, Six Moons and Z-Packs provide a wide range of lightweight shelters that will survive most conditions. I wanted serious storm-worthiness so I've made my own, with the design goal of being quiet at 40mph and surviving 80 mph without damage. It weighs 800 grams, has an excellent porch for gear and cooking and is pretty much as strong as your Hilleberg.
Pack: I've never bought into the frameless idea - once you're carrying significant weight a frame that weighs very little hugely improves the carry. Your 120 litre pack is staggeringly large. My base volume is 25 litres with 1.5 litres per day allowance for food. I've made my own pack on ergonomic principles, but there are plenty of good lightweight options from vendors like Z-Packs, Exped, Granite Gear, ULA and many others.
Sleeping: I don't compromise on this at all because I'm a basket-case if I don't get a good kip. Vendors like Exped and
Therm-a-Rest provide warm and comfortable sleeping pads for around
450 grams / 16 oz. For your bag, go for down and consider a quilt -
they give more insulation for the weight, and I personally find them
less restrictive and more comfortable. Enlightened Equipment provide
a good product at a very fair price.
Beyond the big 3, simply focus on sourcing the lightest option for everything - the grams add up. For example my Opinel No 6 knife gives me a practical 7cm blade at just 30 grams. My Petzl E-Lite gives me 70 hours of camp light and on-trail walking for 28 grams, and a set of spare batteries is 6 grams. It's the cumulated impact of lots of small decisions like this that makes the difference.
For more detail I'll point you to this excellent gear list by one of the most experienced and respected people in the field.
Depending on your weight and mileage, you should be budgeting around 1 kilo / 2.2 lbs per day. This assumes you focus on foods with high calorie density - do a quick Google and you'll find many blogs exploring this in detail. I've read widely on this and every credible expert gives similar advice. For short trips you can pack a bit less and lose a bit of weight on the hike. For longer trips you simply can't undereat of you'll start cannibalising muscle.
Hope this is helpful!