What is the best plaster for earthbags and rammed earth walls in northern Idaho?

I've been experimenting with alternative building for 3 years now. I'm ready to start and earthbag foundation/wall for the next building. We are in the Panhandle of Idaho (about 23 inches of rain/year) and a different zone and precipitation than Arizona. I can see where cob would work well in Arizona but I don't think cob will work to cover my rammed earth tire wall or the earthbags. I'm cognizant that you don't want to mix/match too many mediums without a layer for condensation between them so there won't be a weak point, but what is the best thing to use in the plaster for 16 inches up from the ground for these kinds of structures? Earth mixed with cement? Proportion of clay? Papercrete? I'm needing a bit of forward movement on this. Can I use the same plaster for both projects?

Acrylic stucco work very nicely for these structures that tend to flex and move just a little as they settle.