An '04 Tahoe most likely has the 4L60E 4-speed transmission. If you don't have the full tow package I'd urge you to install a good size transmission cooler.
The Tahoe probably has the brake controller wires taped up under the dash (my '04 Envoy did.) Get a good brake controller (Prodigy is one highly rated one) and splice the brake controller harness wires by function and not by color. I don't think the Tahoe is plug 'n play but I may be wrong.
And you'll need a weight distribution hitch. The Tahoe will have a soft suspension & you'll need a WD hitch.
Then you'll need the mundane stuff - sewer hose, fresh water hose & pressure regulator, wheel chocks, and levelling blocks. A 20 to 30A adapter and maybe an extension cord if you camp with electric hookup.