New TV - 2019 Tahoe

We upgraded our tow vehicle.  We traded our 2010 Highlander for a 2019 Tahoe.  We loved the Highlander.  It towed Wood River Pod (179 HR) great with the e2 WD hitch.  It was tough with the v6 and our mountains here in Idaho and Montana.  It did it, but I felt like I was always kicking it with spurs.  I think the V8 Tahoe and no more unibody frame will make a huge difference. 

Here lies the problem at hand.  Today I went to adjust the e2 (trunnion 6,000) hitch.  With the Highlander we had the shank that came standard with the e2 in the up position to get to our coupler/ball height at 20ish inches.  I turned the shank downward and could only get the ball down to 25ish inches with the lowest holes.  I need to drop another 5 inches.  What length downward shank do I need?  Frankly I've tried watching videos on etrailer and youtube, but it's not creating easy math for me. 

My current shank is this.  The arm that goes into the receiver is 12 inches and the rise or down arm is 8.5 inches.  What length drop do I need to add another 5 inches of drop from this shank?

Does anyone tow an rpod with a Tahoe?  What have you done?  Or how do I figure how much drop I need?  Do I need this?

Thanks for the help.

Jeff

Thanks Stephen.  I went to the Equalizer website after some more browsing.  They have a shank selection tool where you put in the measurements (ball, receiver, coupler) and it'll provide you with the right shank.  The tool came back with the one pictured above.  Prime from Amazon.  It'll be here Wednesday.  When I get it hooked up, I'll send along some pictures of the new setup and TV.  I'm really excited. 

Thanks

Thank you for asking. My dad is doing better. He is pretty stable now. He had a skin cancer removed from his nose a few days ago and needs another one removed from the top of his head. He is using a walker now because he still isn't the most steady walking. He does not like it but he did trip with it and fell, so even a walker does not prevent all falls. We had a good talk with my mom today and dad mostly listened. I'm glad we went down there over Christmas. Ruth has her upcoming knee replacement and I will likely have surgery on my left thumb (CMC joint arthritis) in March. These will limit our travels probably until late spring. Even then, our trips will likely be more local this year.

It will be interesting to hear how the Tahoe does when towing. 30 mpg in a pickup truck is great, even if it is only on the flatlands. I remember when our daughter had a Dodge Ram and she said she was only getting around 13 mpg and that was without towing anything.