Best to not trust dealers for things as specific as WDH set-up. It's not that they are all incompetent buffoons, but they may not take the necessary time to set it up correctly ... as opposed to just blindly applying a rinse-repeat setup that works for 80% of the vehicles.
Best place to start is the manual for your WDH. You can usually find these online. There may even be some videos (for example, Equal-I-zer 4-pt hitches have good manuals and youtube videos ... not sure about Reese).
Then, take note of how yours installs and adjusts -- there will be some mechanism on the hitch that will adjust more or less weight to your front axle. You need to know what this adjustment is (sometimes it's washers to adjust certain angles), because you will likely need to do this once or twice.
Though you need to follow your own brand's manual, they typically work like this:
1. With your truck unloaded (no trailer) and on level ground, measure the distance from the ground to the wheel/well fender above your front wheel.
2. Drop your trailer on the truck's hitch with NO weight distribution engaged. This will cause your rear to sag and your front to come up.
3. Repeat the measurement in (1) to see the new height of your front wheel well/fender. Do the subtraction to see how much the front was raised.
4. Remove the trailer from the truck's hitch. Now drop it back down WITH the weight distribution mechanisms engaged.
5. Repeat the measurement in (1) or (3) to see the new height of your front end.
6. Adjust the weight distribution amount so that when you repeat (4) and (5) that you return at least half way back to the measurement you made in (1).
For example, I measure my front at 35". Then, I drop the trailer on it and my front raises to 37". That's 2" my front came up. I need to get down to at least half way back, or 36" in this case. I don't want to go over. So, I'll adjust the WDH properties until my front end is somewhere between 35 - 36". It could take a couple of iterations.
(Note that I already assumed that you adjusted your hitch head such that the trailer is level when dropped onto the ball -- you can do this theoretically, too. Measure the hitch height of the trailer when leveled and then set your ball height/hitch head to at least this height)
Here's an example of the measurements: