Why not just continue the discussion here? I read the thread because I recognized Brett's name--going in search of another one now seems redundant.
I'd make that rechargable batteries and a couple of rechargers. Less weight overall and much more savings.
Seeds for planting potted garden stuff from home. You can certainly mail order packets later, but why not tuck in some seeds for lettuce, tomatoes, green onions, and zuchini now? They're light. Or is Guam one of those biosphere reserve places where they're trying to eliminate non-native stuff? My guess is that the U.S. has been entrenched there too long and has polluted the place with bugs, birds, cats, rats, all of that by now. Pack the zinnias and salvia and live dangerously!