Here's a link to a calculator that may help.
You are pretty much on track.
Note: Tongue weight is not a constant number. It fluctuates during every trip, and, it can be greatly affected by holding tanks. On average, about 12 percent of every pound you load into the trailer, will add to tongue weight. However, that depends on where (in relation to trailer axles) it gets loaded, and what gets loaded. My trailer, for example, has four holding tanks. The black and grey tanks are directly above the axles, and have little to no affect on tongue weight. My galley tank (35 gallons) is far forward of the axles, and adds about 200 lbs on my tongue weight. My fresh water tank (35 gallons) is in the rear end of the trailer. It takes weight off the tongue. During a camping trip, my tongue weight can be anywhere between 975 and 1200 lbs.
If you're NEVER going to tow with water on board, or with loaded holding tanks, you won't need to worry about this much, but, you should be aware of this possibility.
18 Nissan Titan XD
12 Flagstaff 831FKBSS
Wife and I
Retired Navy Master Chief (retired since 1995)