CDC.
The main thing about a command assesment ride is to make sure that you approach it with a mind set that says that whatever you do, in whatever scenario,will be what you will do on the day in real life.
If that means you may come into direct conflict with the trainer in the back, it doesn't matter, so long as you were legal, safe, and sensible.
Above all fly your sims for yourself and just ignore what you think the trainer wants you to do.
Believe me when I say that I have just come out of the simulator having suffered probably even worse symptoms than you describe, the difference is that I have been a jet Captain for 19 years! Sims still send me to the pits of depression, however at the end of the day I just have to say ' sod it, sod him!, and I'm just going to do what I would do in real life' Funnily enough they seem to keep signing my licence. God knows why!
Good luck and send a PM or a mail if I can help more.