School me on heated tanks and enclosed underbelly stuff

I've got electric pads, and ducted heat (although I don't know how well it heats anything in the underbelly) and have survived several days with temps in the mid/upper 20's overnight with no issues (that I know of anyway). I turn on the tank heating pads and run the furnace at night at about 55 degrees. Also leave all the cabinet doors open so heat can get into the nooks and crannys where the plumbing hides. Did have to bring in the fresh water hose since it's not heated.