[Taipan]

From my own personal experience; Sargassum Triggers are one of the most docile and peaceful of the Triggerfish family. In theory; any Trigger that belongs to the genus Xanthichthys are generally "reef safe with caution". At the end of the day....they still are Triggers. However; I have had Sargassum and Bluethroat in a reef environment that included SPS, LPS, Cleaner Shrimp, Blood Shrimp, Pistol Shrimp. smaller fish (such as Blue Eyed Cardinals, Clownfish, Juvenile Harlequin Tusk, Wrasses) without issue.

I generally try and keep them well fed to stave off temptation. Over time I will even skip a few feedings and observe how they react to less food. Mine have had no increased aggression towards tankmates with a decrease in feedings.

Triggers are very personable and have unique personalities. Mine eat from my hand if I let them.

From the description of your FOWLR environment; I think things will be fine - especially if you introduce the Sargassum trigger as the last/final addition. They aren't the most popular or common....but very much worth the wait in my opinion. Good Luck.