New Scouts and Listening Issues

I am currently the SPL of my troop and we recently took a short backpacking trip up in the Flagstaff area of AZ. Two kids new to backpacking came along. One had actually already been on a backpacking trip. We had a month (4 meeting) dedicated to backpacking so as not to have anyone over pack/ under pack, etc. The two scouts along with about 4 middle scouts (12-13 years) brought about 40 pounds of gear for our 10 mile trip. We shook them down at base camp. About a mile into the trek the two new backpackers couldn't go any farther. We thought it was just because they were telling themselves they couldn't do it. About 3.5 hours later we got to the campsite and we opened their packs and the 4 middle scouts. Turns out every single one of them put the stuff we took out of their pack right back into it.

How do I, as a SPL, deal with this issue of listening to instructions?

P.S. I have redone the entire troop so that it is communication crazy. Phone trees, e-mails, paper handouts, announcements to adults.