Carry your defensive weapon on body, with a spare. Use that go bag for water, food, protection from the elements, etc.
If your gun isn't on you, it won't be there when you need it. My BOB is filled with enough stuff to last me at least a few days, if needed (and we have one for each member of the family). If I'm caught without it, I'll still have my G19 with a total of 33 rounds on me, and likely my LCR with another 15 rounds. The only "gun" related items my BOB has is a box of 9mm...just in case.