I believe one base station is enough for headtracking if it is in front of you.
Second base station is needed mostly for controllers when first base station is obstructed by your body.
I play MSFS with Reverb G2 and don’t use controllers (I have them but did not touch them in a while) - game can be started, switched to VR, and controlled (menus and flight controls) with just mouse and keyboard (and optional joysticks/hotas).
I use WMR, but I would expect it should be same with Steam VR (regarding ability to play without controllers).
I am using the Valve Index, similar as I do with Elite Dangerous, I just start SteamVR and the game. Then I put on the Index and don’t even bother with activating the controllers. They just stay off completely.
In MSFS, i activate CTRL-Tab to switch to VR and press Space to center the view. Actually I got used to doing so as soon as I hear the game music starting at the first loading screen after the Logo animations are done.
If you remain seated, one base station should be enough, but if you are playing games, which are played while standing, you should have two base stations. As mentioned before, having just one station will cause tracking dropouts when you move the controller behind your body, so the sight between the base station and controller is obstructed by your body.
The most ideal position would be mounting the first base station in front of you a bit above the height of your head being slightly tilted downwards facing you and the second mounted at the same height but facing your side.
However, also other configurations work, I myself have my two Index positioned in a V-Shape as you would expect from a decent hifi stereo setup, because my room doesn’t allow otherwise and so far I have no issues with that positioning even thoug it isn’t ideal.
There is no PC setup that can currently handle Vive Pro 2 and MSFS. Even 3090 is struggling with Reverb G2 without lowering the resolution and Vive Pro 2 has even higher resolution. I guess at least it will be somehow futureproof for when 4090 releases.