As I said in my email to you, you should do whatever you feel comfortable doing. You're not a cheapskate if you don't tip, and there is NO requirement for you TO tip. I hope you didn't take my email response in which I outlined what I tip on Holland line ships as being indicative of me calling you a cheapskate.
Please, just go and enjoy the trip and don't let the tipping question worry you. And you're NOT being a cheapskate!
Grace and Peace,