jbornhop. Even though you have said you live near St. Louis, why not take a moment and add your location to your profile and have it show when you post. We always want to know where one lives, whether giving advice or asking for advice.
If you go to the "Plumeria" forum, you can find dozens and dozens of posts (many by yours truly) about taking cuttings. Do you happen to know what specific variety your plant is? I take dozens of cuttings every year, because like you, I have to move all my Plumeria inside for the fall and winter months. In fact, just this week I have taken over a dozen cuttings. If I did not regularly cut my tips/branches, some of my plants would be over 20' tall. Again, like you, I begin my love for Plumeria while on Maui and brought back three tiny cuttings over 25 years ago. Believe it or not, I still have those three plants and now their bases (that started at less than 1/2") are 5-6" thick.
If you would like for me to chat directly with you privately, you can easily T-Mail me by clicking on my name and then clicking on "Send a T-Mail". I would be more than happy to help you.