How much does he move around? It might be quicker to manually move an adjustment layer/null by setting keyframes for each minute, then checking coverage in each minute section, adjusting where needed.
Another option would be to use a proxy for faster working, but to be honest you might spend just as long rendering out the proxies.
Finally, I’ve just learned that YouTube has an automatic face blurring option. Never used it myself but that might be the simplest solution if it works.
http://www.YouTube.com/ShiveringCactus – Free FX for amateur films
https://shiveringcactus.wordpress.com/ – FX blog