Did you go straight through to ride a 600k in 33 hours?
getting back is almost always easier. Although I have heard of headwinds on the way back. My hope is to get far enough ahead on time that I can stop at every roadside cafe that has a crowd of cyclists drinking bear outside.
Other than getting totally out of whack on my sleep, the other problem I had on PBP was food. Trying to live off of the controle food on PBP just didn't keep my legs happy. On the way back, I went into a grocery and bought some chocolate. Other than giving me severe heartburn, that worked really well for me. And avoiding the lines at the first food stop would have saved me tons of time.