I think some banks are back in the mkt offering base rate derivatives to their institutional clients, so it's hedgeable in theory, but not in practice. The best you can do in the mkt is SONIA swaps, which are the closest you can get to base rate.
As to your query, DT, I think the only/best way you can do this is by owning some far OTM puts on one of the UST futures contracts, such as FV. For example, the furthest strike I see that has a price in Dec10 FV is 117, which, if it expires ITM, would imply 5y note yielding arnd 2% at delivery. This put costs a tick (1/64th), i.e. $15.62 per contract, but you'll have to keep rolling it. Let's say the event that you're looking for occurs suddenly in, say, 2.5 years. By that time you would have paid a cumulative premium of roughly $156.2. If 5y notes then trade at 5% yield, your put would be worth arnd 13-38+, i.e. arnd $13.6k.
This is a very rough calculation that makes a variety of arbitrary assumptions and ignores other important aspects of pricing.