Wow....great information. Yes, the lot is in North Florida & can get pretty cold in December & January, I had RV sewer hose crack this year after 3 nights of 20 degree temps. I really want to use the pvc pipe to have a more secure setup. The property owner said never any issues with the tank. It was not used at all for over a year.
I don't leave black water tank open but do empty it every 7 days. After draining, I dump in Calgon water softener, All detergent & 2 gallons of water into the toilet. Been doing this for a couple of years & have had no issues.
Since I won't be able to do this myself, so not sure if I should call a plumber or a handyman service. I have not found anyone in the area who does RV work and renovations but if you know of anyone in the Leon County, Florida area, let me know.
Thanks for all the invaluable information. I can see this is the best way to find answers - how much better than folks who have RV's. Appreciate you all.