Can you run P2Pool without having to keep the blockchain updated? I'm guessing the answer is no, but I thought I'd ask anyway.

I'm running my miner off a USB pen at the moment and I'd like to run P2Pool but the main issue for me is there wouldn't be enough space left on the USB pen to store the blockchain.

Is there a way I can run P2Pool without having the blockchain stored locally?
You could run the Bitcoin client on a separate machine, and connect to it over the network.