That's a good idea, that will also show you if there is anything you might need or want to do.

 

Here ya go.

https://www.etrailer.com/faq-ballmount.aspx

Another one from Curt:

How to Measure Hitch Height, Hitch Drop, & Select a Ball Mount

Hitching up your trailer requires a secure connection. This means choosing the right trailer hitch ball mount for your towing setup. In this guide, we will walk through some of the considerations for choosing a ball mount, including measuring hitch height versus hitch drop, how to select the...

www.curtmfg.com

 

What i do is measure to the top of the receiver hitch.
Connect trailer to truck with whatever you have.
Measure again to top of hitch.
That is how much your truck is going to squat with the load.
Now disconnect trailer and level it. Measure to your bottom of the coupler.

Now you know your truck height loaded and unloaded and the trailer height when level.

 

Hmm, I wonder what @cooperlio will do to his posts soon...

 

I have an adjustable hitch on the back of my 2500HD similar to this Curt so I can change the height properly for each different trailer that I have to pull.

Amazon.com: CURT 45900 Adjustable Trailer Hitch Ball Mount, 2-Inch Receiver, 6-Inch Drop, 2 and 2-5/16-Inch Balls, 14,000 lbs , Black : Automotive

Buy CURT 45900 Adjustable Trailer Hitch Ball Mount, 2-Inch Receiver, 6-Inch Drop, 2 and 2-5/16-Inch Balls, 14,000 lbs , Black: Ball Mounts - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com