If your goal is to be monolithic, it is good to have "fundamentalist." If your goal is to grow and accumulate Bible-believing Christians as members, then it is better not to have "fundamentalist" in your constitution.
Using the term "fundamentalist" in a constitution is a good idea if you want to limit membership to only those who identify with the term. So, if that is your goal, then it is good.
If, on the other hand, you want to welcome those who profess to be born-again, believe the Bible, and agree with the general beliefs of the church, then no.
The way I like to express things is, "we believe in the fundamentals of the Bible" or "we believe in the fundamentals of the evangelical faith" or "we hold to the fundamentals of Biblical Christian faith."
