If it "isn't even mentioned in the Constitution," (and it's not), then it's protected. The U.S. Constitution enumerates the powers of the U.S. Government. A right does not have to be mentioned in the constitution to be a constitutionally protected right by virtue of a lack of authorization for the government to take it away.
From everything I've read about the "Right To Privacy", starting with Alderman and Kennedy's book in '96 (which got me to start paying attention to what SCOTUS and SCOTUS nominees were saying about privacy as an actual right implied by the 4th amendment), it is very much up for grabs as to whether we have a Constitutionally inviolable right to privacy.
I hope we do! But an argument backstopped on the notion that we do doesn't seem very strong.
There are those — including some of the authors of the constitution you're talking about — who believe that rights do not come from written constitutions or governments, but rather that it is to defend the rights that we naturally possess that governments are erected by the peoples of the earth, with written constitutions or without them.
Perhaps this is a naïve view of governments and of rights. But it is this view upon which everything you are discussing is contingent. The alternative would seem to be that might makes right.
Rights are not absolute out in the real world. There are always tradeoffs, especially when various rights come into conflict with one another. The second amendment clearly states that "the right of the people to keep and bear arms shall not be infringed." Does that mean that it is unconstitutional for me to be prevented from bringing an Uzi onto an airplane? The various political and judicial processes that have been established are how we balance these various rights to achieve some condition that most of us are satisfied with. Rights may not come from written constitutions or governments, but those creations are what we use to negotiate amongst ourselves when various rights appear to be in conflict.
