Anyone else have 8 lug hubs on their trailer, and have any idea what their tongue heigth is?
Just use the jack to level the trailer (measure the distance from the main beam to the ground in the front and back).
Then, hook up the trailer and measure the distance to the ground without any weight on the tongue, then measure it with the tongue fully loaded- that's the sag distance.
Then, buy a hitch that will get the trailer back to level (+ or - your current hitch).