If a fiver is a fifth wheel, it will be taking up some space in the bed for turning radius, hitching etc. The hitch plate alone is heavy and big. Not sure if your bed is short or long. As for water storage, water is heavy and it shifts weight around when driving. <br><br>I would try and get creative in my water needs. (Well, I have for myself and my condition/area) Not knowing where and how far you will be from water and the expense of obtaining the water, I say plot it out so you don't have to carry as much. This is something I learned when I through hike the AT. While researching and planning I found that water sources were about 8 miles apart. Needing 2-3 gallons of water a day for cooking, cleaning and drinking, I planned on stretches of about 16 miles a day. Camping near a source for the night gave me the ability to have water close for my dinner cooking and clean up, morning wash up and enough to get me to the mid-day replenishing source, which piggy backed me to the 2nd water source of the day which in turn started the cycle all over again. <br><br>You could apply this same train of thought in your problem/solution system, only on a larger scale. <br><br>Years ago when I took wilderness survival/first aid and rescue classes one thing that stuck in my head was this saying, "The more you carry in your head, the less you have to carry on your back." <br><br>Learning to conserve water is also high on your priority list. Brush teeth with a few shot glasses full, wash hair less often or use waterless soaps. Keep yourself clean is of utmost importance to health and does use a bit of water, just find ways to lessen the amount and still fit the bill. I keep my hair short, where military BDU (instead of jeans), where less cotton clothes, etc. All these things help conserve water. Little and often make much.<br><br>I carry 15 gallons with me. Two 7 gallons and a one gallon container. But water is always close and with my stores, I can go a week if need be. Look into a Sawyer water system. For $80 your potable water needs can be solved and is the best utility system I have found for potable water needs there is.<br><br>Good luck, hope this got the wheels spinning for your issue.