Hello there! I am in need of additional water due to my health condition
What kind of health condition?  We both require water to make it thru the camping trip
Due to my blood pressure medicaton, I need to stay hydrated at all times. It is more important for me to drink rather than eat which is why I would give you more food in exchange for more water for me
That is understandable but if you were to get the majority of the water I would want all the firewood and 2 packages of food 
I am happy to give you 2 packs of food and the lions share of the firewood but I think I need 1 firewood. I am not a good firestarter
So are you ok with me getting 1 package of water and 2 firewood and 2 food
I am absolutely OK with that deal.
Just need to make sure we are both have sufficient supplies because I dont know about you but living off the land would probably be disastrous for me
I appreciate your concern. I did bring a little bit of emergency food
I think we have struck a deal then.  Unless there is anything else to be discussed I think we can conclude the negotiation 
I agree
Thanks for the quick negotiation and I am going to submit the deal on my side