Unless you plan on riding in the rain, for your purposes a rear rack with a solid top would probably be adequate. It won't keep your feet or drive train clean, but it will keep the skunk stripe from puddles off your back.
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"Let us hope our weapons are never needed --but do not forget what the common people knew when they demanded the Bill of Rights: An armed citizenry is the first defense, the best defense, and the final defense against tyranny. If guns are outlawed, only the government will have guns. Only the police, the secret police, the military, the hired servants of our rulers. Only the government -- and a few outlaws. I intend to be among the outlaws" - Edward Abbey