There's not a lot of space under the 4 doors. I have the same DJM kit you do but used different springs (General Spring 2200 lb capacity - they're very stiff) because the stock ones were too soft once the travel was gone. I had issues with the front too though and ended up with a 1500 lb/in spring in the front vs probably 1100 lb/in for the DJM drop spring, so the truck felt very unbalanced when driven aggressively.
I'm still trying to find a good rear shock option because most drop shocks are too soft for what I'm after, and/or and too long. I actually left the C notch off of mine and just replaced the stock tall bump stops with universal Belltech progressive foam stops that were a little over an inch shorter. Reason being, allowing the travel with the notch will let the axle hit the stock exhaust, the fuel filler pipe, and possibly the floor of the truck. Also make sure you check the crossmember that runs over the driveshaft. Mine interfered on larger bumps which is a good way to break a lot of things.
The rear of your truck is very low for a Tahoe and a lot lower than mine, but I do like how it looks if you can make it work well. if not and you want to pull the back up a little, make sure you don't also have drop shackles in the rear.
600 lbs on the hitch, probably 500 lbs of stuff in the back:
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no empty shots, but one with just the bike on the back. It sits about an inch higher in the rear without it.
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