You could use the Jetstream as an outer layer with light base/mid-layer while hiking around and then add the puffy of your choice when you stop. How cold that will work to depends on the mid layer you’re wearing and tolerance for cold. And of course which puffy you choose. At 11k in December I’d go with about as warm a setup as I could. Realize the Jetstream, and all other shells, have no loft and thus very little heat retention.
