Newbie Question:Advice on used AllWeather TC for work travel

Thanks B, and jefe! I'm getting all the option documented and working to find a used Bigfoot or Northern Lite as we speak. I'm looking through all the western us states right now. Anything I should look for or avoid while searching to help narrow the herd?
B, do you use your fresh water black water system at all, or do you follow the regimine described in previous posts, containers of water, RV anti freeze to flush, and a dry fully winterized fresh water tank?
Happy Independence Day to all!