You can go through all kind of gyrations but as you discovered, before you hitched up the TT, the weight on you truck axels is 760 lbs. lighter than after.
How the weight was redistributed by the hitch, ball height and, spring bars is a function of their set up. In theory you can reduce the spring tension and increase the tongue weight.
I found I had spent a lot of time chasing my tail over these things, only to find a 160 lb. shift because I added or use up 20 gallons of gas. Or, this trip the fresh water tank was full instead of 1/2 full.
