I'm a new Chinook owner since December 2018. This is my first RV and also the first post and forum I've joined. Please forgive my naivete and general inexperience, but I just went through something similar in regards to a low rear end.
I purchased the unit over the internet from a dealer in Denton, TX, flew into DFW and drove it 2000 miles to Northern California with several stops in the Southwest. No major problems or surprises along the way other than a leaky valve stem extender and a leaky house water pump. Oh, almost forgot the 50 MPH crosswinds through west Texas with truckers pushing past me and the 80 MPH speed limit as the dust storm light blinded me as it reflected off my white knuckles.
Before flying to Dallas, I had the unit mechanically inspected by a third party and they gave everything the green light with the exception of a few small things and the fact that the shocks look like they were the originals. Oh, did I mention that the rig has 115k on it?
I had asked the dealer and also the mechanic if MORryde was installed, but they gave it an "I don't think so..." answer. When I arrived to pick up the rig, one of the first things I looked at was the suspension. Yup. MORryde. The shear spring on the driver's side was torn several inches and the passenger side was likewise quite stressed after 15 years and 115,000 miles.
After first taking it to a larger RV center for repair and getting a recommendation for a bunch of front end work (Safe-T-Plus, trac bar, Sumo Springs, shocks) and nothing to address the rear end sag, I ended up finding a small business knowledgeable in suspension - with the exception of MORryde. He said that the frowny leafs were okay, but the non-leaking shocks could probably be replaced with better ones. Though he wasn't familiar with the MORryde setup, he contacted the company and got a quick customer service and subsequent YouTube education. The rest of his education I paid for.

We discussed several shock options and I took his advice based on experience over Koni's, Bilsteins and others.
New Monroe Magnum RV shocks all around plus two new MORryde Shear springs and the Chinook rides several inches higher in the rear and is much more manageable. I neglected to take a before measurement of the ride height before the shocks and MORryde were replaced, but I would say it's nearly three inches. Though I don't have anything to compare it to other than the old parts, I feel it rides and handles well. It's a huge improvement with no more bottoming out or hard impacts over expansion joints or bumps. I would guess that my initial trip through west Texas wouldn't have been nearly as stressful if those components were functioning as they are now.
@The Bluebird, if you haven't messed around with your leaf springs yet, you may want to try finding someone to replace your MORryde shear springs first. Check out the MORryde website and maybe you can find a dealer/installer that you don't have to educate too much.
I understand the stress of having to question every bump, apron and undulation to determine if you're going to drag something. I've scraped my hose carrier and rear step several times. Part of it may be due to inexperience, but part of it is parts.