Aerogear really only begins to make a difference at speeds above 20 mph and even then it's small. It's best used for time trialing and track racing, where speeds can hover around the 25-30 mph mark and in the cases of sprints up to 40 mph without drafting.
If you're on the bike for 20+ hours, I really doubt you'll average above 20 mph for the majority of the time. I think you're better off going with a lighter wheelset, comfortable well vented helmet and geometry that you have spent 10 or more hours at a time on without issues. The weight saved from the helmet and wheelset will save you a little bit of energy on hills and your average speed won't likely be high enough to benefit from aero stuff.
Add in the fact that you can draft and the aero stuff isn't needed at all.