WDH

Any WD hitch with chain links would be easy to adjust accordingly by changing the number of links used. I doubt the full tanks would increase the tongue weight that much that you would have any noticeable problem with your truck though.

A full 40 gallon tank would weigh approximately 320lbs and likely less than 1/2 of that would be applied to the tongue. Are you experiencing sway or bouncing or control issues? If not I'd stick with what you have. Adjust the hitch for the full tank weight and it will be fine if it's lighter.

Living and camping in the great Southwest, I never travel without a full fresh water tank and empty waste tanks if possible. I've camped in parks with failed fresh water systems.

It's hard to explain. I can tell a difference but it's not huge. The camper sits a little more nose down. No sway or any negative handling issues. Maybe I'll adjust the hitch a bit and see how it goes.

That would be my suggestion. You say "a little more nose down", does that mean when empty your trailer is nose down? I would see if I could get it level.

Lets go with the 40 gallon tank. Full it would weight 320 pounds but you say you usually travel with it half full. So, the difference you are adding is 160 pounds. Unless these 160 lbs are sitting directly on the tongue, they shouldn't make that much of a difference.

I say adjust the hitch. If you can't do that then move some of your existing weight to behind the axle.

I notice a tiny bit of difference with no WD between full and empty tanks.

With WD attached, it makes zero difference to the truck.

Load some stuff to the rear of the trailer to counter the water weight rather than making adjustments.