better to adjust wd hitch for heavy load? or for unloaded TV

I would let the numbers decide. Load the bike, gas cans, firewood, trailer full of water and setup your hitch. Take note of how much it squats and how much you level out with the WD installed.

Then if you ever leave the bike at home, measure everything again to make sure the rear end didnt rise to an unsafe level.

Not sure what i would do regarding gas in the truck. Maybe 1/2 tank?

What bike.....tw200 maybe? Trying to think what is small but still heavy.