[...] you are assigned bookbags to carry for identification purposes I have a suggestion run out and buy sonething like this:
http://www.bhphotovideo.com/c/product/388729-REG/Lowepro_34731_CompuRover_AW_Backpack.html
Wich has exactly the camera space you need and has a good amount of space on the top to hold a days worth of travel items like food maps guides or whatever you want it also has 2 fairly sizeable water bottle pockets on the sides to keep your water away from the rest of your gear. This bag also has an excellent raincover and a laptop pocket if you want it. So here is the tricky part, take the bookbag you are issued and cut it to pieces!! using either a needle and thread or just some saftey pins take all the pieces of your issued bookbag and attach them to you new lowepro camera backpack making you easily identifieable to the rest of your group and to boot you make your fancy camera bag look ratty and sewn together therfore detrring potential thieves. I know I know this is the greatest idea anyone has ever heard.
Sounds like a plan, JIP!
I like lateral thinking!