How to protect foundation, sill, and siding from moisture (snow)
better than metal flashing and its excellent ability to repel water/moisture is self-sticking rubberized flashing. Although 15 pound roof felt also is acceptable. Either product should be lapped over by the (if any) house wrap and fastened with minimal nails ,etc. I'm not sure about the problem you have in regards to re-installing the clapboards? Won't they re-install with the original fasteners? or is there concern about nailing through the metal flashing?