Knitting heavier socks: Which approach works best for bulky autumn yarn?

I usually lean toward letting a heavy fiber like that alpaca blend do most of the talking rather than fighting it with a dense pattern. When I worked up a pair of socks last season using a similar rust-colored weight yarn, my hands felt completely exhausted after just a few rows because the stitch definition seemed to be fighting the yarn's natural bulk. I found that the intricate floral motifs I planned simply felt too heavy and created a lot of drag. If you want that substantial feel but need it to fit well around the ankle, I would highly recommend keeping the pattern minimal. A simple garter stitch or even a basic 1x1 ribbing in the foot section keeps the texture looking clean while allowing the color to really pop. It minimizes the amount of yarn you are forcing into specific shapes, which helps maintain your tension.

I'd suggest dropping the highly detailed stitch plan and instead focus on swatching with those size 11 needles for a few inches. See how the fabric behaves; if it feels overly spongy or too loose, you might consider dropping down to a size 10.5 or even a 10. It might give you the necessary density to keep the sock from feeling floopy, even without a lot of fancy texture. The goal is comfort first.

I hear you on the hand fatigue, that heavy alpaca does make the knitting feel like a workout. But I think we might be overthinking the simplification thing. When I've worked up those thick sock weights, I found that fighting the bulk by going too simple actually results in a fabric that feels flimsy, not substantial, which defeats the purpose of using such a luxurious fiber. My approach has been to embrace the weight, but manage the stitch structure. Instead of dense cables, which require huge tension, I usually opt for a simple moss stitch or a subtle ribbing, maybe switching my needles up by just half a millimeter from what the pattern calls for. For the rust alpaca, I'd probaly move to 11.5 mm needles just to bring the gauge up slightly without sacrificing the texture. This gives the finished sock that satisfying structure you are looking for, making it feel truly dense and substantial around the ankle without giving your hands the absolute worst time. It lets the beautiful drape of the alpaca do the heavy lifting.

I think the issue might be where you are pulling the yarn through the loop. I once worked with a similar rust alpaca and found that switching from my standard knitting needles to a set of bamboo ones made a huge difference in how easy it was to work. The bamboo just felt smoother on the fiber. You don't necessarily need to change your stitch pattern to solve the bulk problem. Sometimes the density of the fabric changes when you are knitting right up into the cuff area. Have you thought about using a slightly tighter tension right at the rim to help it sit better on the ankle without making the whole sock overly dense?

I completly agree with the earlier point about letting the yarn do the heavy lifting rather than fighting it with a complex design. When I worked on a set of those heavy rust socks last year, I learned that if the pattern is too busy, my tension would get totally thrown off. I'd end up with some sections too tight and others that are loose and puckered. Switching to a simple garter stitch made the whole process much smoother becasue I could maintain a consistent tension without having to worry about forcing stitches through the bulk of the alpaca fiber.