It's still way too heavy for the typical Camino for most users that walk between say April to September
Ten years ago, I started with a 40L pack on the
Camino Frances - this year I did the Camino Norte with a 12L pack, the Gregory Miwok (women's version also available) - it weighs 1lb 30z not 3lbs for your 40L pack
I could go for a lighter pack but I like the back that reduces moisture transmission to my shirt, it can fit a bladder if wanted (water is the most vital necessity along with comfortable shoes) and it's robustly made (unlike my Lowe Apline 14L that preceeded it)
Given the 12L pack, the question is less about weight but more about volume - I have to go with a silk sleeping bag liner rather than a sleeping bag (but the liner is much cheaper than an equivalent warmth bag) - I then carry up to 2 x 1.5L of Aquarius plus chocolate inside plus 2 x 0.6L Sigg bottles outside
There's still some room left - for a rain jacket (either 100g of Berghaus or 250g of Haglofs - the latter is GoreTex pac-lite, the former is still pretty good) - for spare polyester shirt, underwear, socks, buff, hat, guidebooks (CSJ, Cicerone), Compeed and a few other things
More like 5-6 pounds plus liquid