I've got a Gitzo GT 5541LS with a Wimberely WH-200. It's a beast, but I never have to worry about stability. I'm a very fit woman in my 50's, 5'7" and I climb down cliffs with the Gitzo attached to a ThinkTank Glass Limo with a 400/2.8G and a D5 or D500, so portability is subjective. I'll shoot with a 400/2.8, 1.4x TC III and a D500 on it and it's solid. It is taller with the WH-200, but the tripod is pretty tall on it's own and works for odd situations, like his. It also folds down to shoot from about 6" off the ground.
My feelings on tripods are, get something that more stable than you need for your longest lens set up, so you're ready for anything. Pick up a second lighter duty tripod later later for other stuff. You can always put a 14-24 on the 5541LS, but you can't put a 400/2.8 on a 2 series.