Philip, do you think it is possible to use the cross country setup you recommended but with a light AT binding (does light make it snomo?) so I can lock in my heel on good downhills? And how would your recommended setup work with a heavy winter camping 65L+ backpack? I liked how you emphasized a more economical solution as AT setups seem like a pricy investment and yours sounded less pricy. What binding/boot models might be good starting points to achieve this effect?
Light or crossover XC ski gear is very unlikely to have any sort of binding mount reinforcing plate at the heel where the mounting screws would go in, so you would probably just tear the heel piece of the binding out when you locked down and put a lot of force on the ski. I would only put AT bindings on an AT ski. But the Voile Objective BC skis are quite light and a SkiMo tech binding can be extremely light and minimal. But, again, that’s expensive. And putting a tech binding on a XC ski (which we already discussed is a bad idea) and getting AT boots puts you back close to the cost of a dedicated AT setup, so there aren’t real savings there anymore.
I’d rather be a little under-gunned traveling on light gear on rolling terrain than dragging a heavier and slower AT setup along where that is overkill. But light ski touring really isn’t my area of expertise. As was mentioned earlier, refer to Luc’s page on ski-touring equipment. His page on fast and light winter travel is also worth a look.