hi, well the main things to put in (well i think anyway) are a meths stove, a wood stove and the mess tins, fire lighter, matches, lighter, kindleing, hatchet, 2 knives, first aid kit, water purifier tabs and straw. wool socks and wool jumper and some combat trousers in a sealed vacume bag. And some army rations,.... That way no matter where you have the stashes you have the basics to survive. one man tents and bivi's are great as you can put all the gear into one small rucksack and hide them.
you can look on
http://www.militarymart.co.uk/index.php
they have some good gear that dont cost too much. I'm doing the same kind of things, and find army gear is best for hiding away for the long term
they have Tri-Laminate PVC Dry Sack Bag in the site, so that might help