I purchased a bladder tank and small pump on Amazon this past year to use during a 3 week hunting trip. There is water in the CG at the comfort station, but water at the sites is turned off. The process worked really well. Here's what I have and it packs into a 12"x8"x6" tote.
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
I chose a 120 volt pump, but they also have a 12 volt DC option if you don't have power and are running primarily on batter. HTH