I have several older Gitzo Series 3 Systematic carbon fiber tripods in various configurations.
Besides the Systematic, Gitzo makes Reporter, Mountaneer and Traveller tripods. These other three series incorporate center columns. What sets the Systematics apart is that they are offered without any center column, with just a platform on which the head mounts. This makes for the most stable possible setup... as you've discovered, having to raise the center column on your tripod to have sufficient height. There is the option, if preferred, to fit a center column to the Systematics. Gitzo offers both a Rapid style and a geared column to fit them. There's also a Leveling Platform available, which takes the place of the center column (I have these on two of my tripods which are used with gimbal heads).
One is a G1348 Mark II, which uses 4-section legs to raise it to 72" tall
without center column. Even taller with a center column, of course. But by the time you set even a smaller head on top of it and the camera on top of the head, I am certain it would be more than tall enough for you.
You mention using a D500 with Tamron 150-600mm. That camera probably weighs about 2 lb. and the lens another 4.5 lb. This would be no problem at all for the Series 3 Systematic tripod leg sets, which - depending upon the model - are rated to support between 33 and 55 lb. My older ones are rated for 33 lb. I think and they have no problem handling an 8 lb. 500mm f/4 lens, 1/2 lb teleconverter, 2 lb. camera, another 1 or 2 lb. of flash, flash bracket, battery pack, not to mention about 3 lb. of gimbal head and 1 lb. of leveling platform. I even sometimes hang a camera bag or backpack under the tripod for added stability, though it's hardly needed.
The modern version GT3543XLS is "extra tall" (about 78") and rated for even heavier load capacity: 55 lb. This current version also uses non-rotating leg design that makes them easier to set up (the older models like mine, you need to loosen and tighten the leg locks in a particular order). Unfortunately, the GT3543XLS lists for $950. And that's for just the leg set. The GSLVLS Leveler, which I highly recommend if using a gimbal head, costs an additional $200. It sounds as if you already have a head to use on it. (I bought my G1348 II used, in like new condition with an older style G1321 Leveler and shipping included, for about $425. I also have the older G1318 Rapid Column, which I sometimes use instead when doing macro work, since it can be reversed to hang the camera and lens below the tripod and makes for a very stable setup.)
Gitzo stuff is great, though a bit pricey! Really Right Stuff is too, but it's even more expensive than Gitzo. Nest appears to be very good and an excellent value. Feisol is another brand with what appear to be some impressive "tall" tripod models.
Look at it this way... a tripod bought right will last a lifetime. And you'll enjoy using it because it actually WORKS. It will usually end up costing less in the long run, buying a more expensive, but better tripod... than having to replace cheaper ones every couple years when they break or you get frustrated with them. I've used one of my Gitzo for going on 20 years. I've got another heavy duty Bogen (now Manfrotto) that's too much to haul around (it's more than twice the weight of the Gitzo), but still works well "in studio", that I paid around $400 for almost 40 years ago! It still works fine too (I just don't have a studio at the moment
).