Welcome to the forum and congratulations! First, driving with the water in the holding tank can be done but many don't. Water is 8 lbs a gallon so that extra weight can impact your towing experience and fuel economy. Tow your camper to the CG with the water tank empty and fill it there (about a 20-40 minute process depending on your tank size and water pressure at the campground). You can also get a site with water and just use your city water connection that directly pressurizes the water lines in the camper.
For the propane bottles, I have a long, bicycle lock cable that I wrap around the frame and bottles. I don't lock my battery, I just remove it when it goes in storage.