You say your truck can handle a trailer with 890# tongue weight.
Not sure how you came up with that, presumably you took into consideration all the people, gear and WDH in the truck, but ok, let's take that.
And you say you want a trailer with at least 13% of the loaded weight on the tongue. ok, that's a good choice to keep sway under control. I would go as low as 12%, but 13% is better.
So your max *loaded* trailer weight should be 890/0.13 or 6846#.
If you pack 1000# then the max *unloaded* or dry weight of your future trailer should be about 6846 - 1000 = 5846#.
Yes, a WDH will move some of that tongue weight back to the trailer, but I prefer to leave that out and treat it as a safety cushion in the calculations.
Do your own calculations, estimate a reasonable amount of personal weight and ignore any high pressure sales person. I've met good and bad ones. And some really, really bad ones.
