פורום דרום אמריקה

hey
i'm going on a 3 months trip to bolivia, peru & ecuador (starting in la paz).
the problem is that i'm starting the trip from new york and backpack covers are different here than what i can get in israel.
it's either a really thin cover against rain (which can't be used against mud in buses) or a bigger cover that acts like another bag you put your bag in.
should i just get both covers or should i take the light one and buy something when i get to la paz?
thanks