The 5th I imagine is a good answer as a lower court may not have authority to rule on that answer.
Yes, I have heard that some people will answer citing either the 4th and/or 5th amendments. That could be another way to go.
Just phrase it so that you are answering the question, ie - My answer is that I assert my 4th and 5th amendment rights regarding this question.
The technicality that they could try to get people on is that they didn’t answer the questions. IN fact you have answered the question, it’s just an answer they didn’t particularly want. And I say I did answer, you just didn’t like what my answer was. Now get off my property or I’m calling the sheriff.