If I filed my N-400 on the based that I have been permanent resident for 20 years, are they going to complicate my process?

Your upcoming marriage will not interfere with eligibility to naturalize, nor will the fact that you waited an unusually long time after becoming a permanent resident to start the naturalization process. You mentioned that you are awaiting an interview date after having filed your N-400 application last month, but note that in the adjudication process for a properly prepared and fully documented N-400 application the USCIS generally takes significantly longer than that to reach the interview stage. At the time of your naturalization interview and examination you will have an opportunity to update information in your N-400, including identification of your spouse. Once you become a naturalized citizen, you will be able to sponsor your wife in a marriage-based adjustment of status application; there is no need for you first to obtain a U.S. passport. Depending upon the circumstances, there could be advantages to petitioning for your wife while you still are a Permanent Resident, and then having the application category change once you become naturalized. For analysis of that detail, as well as evaluation of the many other details relating to immigration eligibility, it would be wise for you and your soon-to-be wife to consult with an immigration attorney who, after learning all of the relevant information, could advise about eligibilities, options and strategies to attain your goals, and who then could offer legal representation in the often complex application process.

If you have a "legit" marriage, you should have no issues during your naturalization process.