By using 14% for TW, you are being more realisic than many here.
The range is usually 10-15%. With 10% being the absolute minimum to avoid a dangerously sway prone setup. 15% is the general maximum only because that is the limit of what the truck/hitch can handle.
What is unique with TTs is that TW can vary a LOT in the course of a trip. FW gets consumed and ends up in the waste tanks, food the same, clothing moves as it is soiled, propane gets consumed and disappears, and many other items change as well. Some here will say that they use 10%.... well they need to be very careful in doing so.
I recommend using 15%, I am over that, but my truck/hitch can handle more than most.
The closer you get to the 10% minumum, the more critical managing the above items becomes... And in my opinion the more limiting your TT experience will be.
Saying you will always fill the water at the campground means that you are limited in only using campgrounds where water is available... IMO, that is a severe limitation... You may be fine with it... And that is OK, but you need to realize that means no boondocking,,,, ever!