Let me start off by saying that no user should ever feel pressured into accepting an answer. No user should ever be pressured into accepting an answer. That being said, I fully agree that the visible accept rate has that effect. And using quite a significant number of my comment flags on inappropriate accept rate comments and pestering, I see such comments on a daily basis. Even more uncomfortable is the fact that this is not limited to newer users, but there are several very high-rep users who are involved in such activities.
All that being said, I don't think that what you propose will help much at all. You can already show your active participation in a question by actively participating in a question. Not just wait for answers to come in, but to actively point out how they do not answer your question. Collaborate with your answerers, address their comments, etc.
While it's true that with what you propose you won't have a negative accept rate on display (whatever qualifies "negative"), explicitly marking a question as having "no acceptable answers" when several users might have done their best to give you an acceptable answer is not going to send a positive message either.
If you have accepted all you can accept, and you are actively trying to get your questions answered, the problem is not with you. And we should not expect you to do anything else to prevent such comments. The problem is with those commenting on accept rate and those pestering others into accepting answers under some form of threat of no longer answering your questions. That is who we should deal with.