DIY Heat And Plumbing w/ No Experience. Shed To Tinyhouse Build

I need running water and heat for my offgrid tiny house before winter arrives so that's what I'm working on today. The water system I'm making is essentially the same as a RV or camper van water. I'm using a 12v pump and pex tubing for the Plumbing along with a 48 gallon fresh water tank. and for the heat I'm using a 12v diesel heater to both keep my Plumbing from freezing and to keep the shack warm.