I know you are loving tooting up your position, but seriously, come on. 30 year = 3% risk free by holding them for 6 months? No. They are only risk free to maturity. If you need to park billions of dollars, the 3-6 month part of the curve is the risk free part. btw, the 30 yr buying hasn't even started yet. Just look at FOMC open market operations. Last operation was in late May 08.
But in 2 years nobody is going to buy this bonds at this prices and thus the prices now should be lower.
How do you know when the storm has blown over and to get out? I guess when you are losing your ass on them then you know it is time to get out.
Just watch inflation. If it goes up from deflation, which is to say, any positive change in CPI, 30 yrs and even 5 yrs will sell off and rates will increase. Correlations aren't necessarily of concern as much as "expectations" are. Information is paramount and quantitative analysis of the yield curve is necessary to glean what the market "predicts" inflation to be. Presently, you can simply see from 30 yrs that the expectation is deflation. When these tick up, as long as you bootstrap properly out 30 yrs, which I doubt anyone on this board knows how to do, then you'll have your answer about inflation expectations. This kind of information is far too valuable to post, and costs tons of money that the individual cannot possibly afford. Institutions can, though.
Learn the process of bootstrapping. If you can become an expert in this... well, actually, you probably can't. Leave that to professionals with Bloomberg and/or Reuter's Terminals. Trust me, if you don't have a bloomberg or Reuter's Terminal, I guarantee you'll get the wrong answers.