Glad to hear you have it working. A few points:
The reason xplane crashes with switching between 2d and VR is due to it running out of VRAM and crashing. The 8KX has a monstrous resolution so if you have any kind of super sampling at all, on a 3080 you will burn through VRAM in no time. I have a 3090 and even that can hardly handle the 8KX.. It'll be worth double checking all of your settings. I would suggest that you set the resolution percentage within steamVR to under 100% - and make sure you only use FXAA - no SSAA at all.
I have developed a little workflow that seems to go quite well for the CL650 - I use a Valve Index now, but it's pretty much the same... You will need the latest version of MoveVR
1 Bind toggle VR to the keyboard ( I use 'v') - and in the settings leave VR disabled.
2 Load up xplane and the CL650 - do what you need to do in the FBO. Set the passengers to arrive in one or two minutes.
3 I have set commands to view the status of FBO actions, and to advance the passenger status to the next stage. (Ctrl-F and ctrl-P respectively)
4 Once loaded into the sim, press the pax advance key - and wait for the phone to ring. Answer it, tell them to send the passengers now.
5. Once you have cleared the dialogue boxes, you are free to enter VR.
6. When the fueller asks you to specify how much fuel you need, you may get a blue empty box appear - open up MoveVR (again, I have this bound to a key command) and open up the plugin menus, the last one in the list will be the fueller options. Click 'move to 2d'.
7. You can then use show desktop in steam VR, or lift your headset and interact with the fueller using the menu on the screen.
8. Repeat that step if he asks you for anything else. (Alternate: use the 2d fuel menu to fuel the aircraft skipping the fueller stuff)
9. Enjoy your flight! Once you land, and you are done, press your toggle VR button ('v') and then interact with the FBO to pick up the passengers.
It probably sounds a bit long-winded, but it works for me every time and I've not had any big issues. Hopefully Toto will soon fix the menus so we can interact with them in VR, then the whole thing will be easy!