Wouldn't it be simpler to have some spare shingles on hand to do minor repairs? It's relatively quick and painless to slide a shingle in. Larger areas are even easier because you don't have to peel back a shingle on top for every shingle you nail down. Anything large enough to warrant using a tarp would probably be worth calling your insurance company. They'd get someone out there quickly to avoid any costlier repairs due to water damage.
Tarp Kind: any? Size: how big an area do you want to protect? It either needs to go over the peak or under the shingles above it to keep water from running under it. Nailed: sure
--Art