Did you want the hypertufa to be highly visible? Or just a mortar between mostly rocks? Or hypertufa rocks mortared together?

If you have rocks, I would suggest a regular mortar to hold them together, it is far stronger and more weather resistant. Windy conditions are always an issue for curing mortars. The normal advice is to protect from the wind as much as possible and keep the surface of the mortar moist for at least 24 hours depending on the admix used, much longer without an admix. This is particularly important in desert conditions.

The wall is small to medium size rocks with the tufa as a mortar, as this is meant to be tempory it seems to the right stuff to use I don't want to have it look too much like the tufa more of the rock I will try to put up a wind barier and I will wrap the walls in plastic to keep them at a steady moisture. will 4mil plastic wrap for windows work for that? Thanks a lot