This what I have done when setting up a new TV. Others may differ slightly...
Get the base weight of the TV loaded as it will be used towing. Full fuel gear etc.
Get a combined weight, TV & AS without WD set.
Get a combined weight with WD set, you may have to re-weigh several times to determine the best set-up.
Your goal is to return as much weight back to the TV steering axle as possible while keeping the entire rig LEVEL
Pay attention to axle loading on the TV and trailer and adjust your tire pressures accordingly.
Here are three tickets from a "heavy" trip we took several years ago.
Notice that when we weighed the rig without WD a significant amount was taken off the steering axle. 760lbs.
After WD adjustment all but 100lbs was moved forward to the TV steering axle, with a portion going back the the AS axles.
Hope this helps...