Even if you are fired, or asked to leave, you can still negotiate a neutral reference which includes the things you are talking about. You are not powerless. Employers are very afraid of litigation after firing based on discrimination (sex, race, age, etc). If you are fired or asked to leave, you can simply begin a dialogue that states in so many words "Okay Jay, I am in agreement with you that it is time for me to leave and I will go and pack my boxes. I will have nothing but good things to say about my time at Hirem, Drainham, and Dumpem. In return, here is what I would like from you: Four weeks of severance pay (assuming they haven't offered better); a neutral reference that does not state I am precluded from rehire; no negative employment references given either directly or indirectly in the industry and (whatever else you think you need). Do we have a deal?"
You are not powerless.