Triathlon is swim, bike, and run. Strongman is Overhead Press, Deadlift, Carry, Medley, and Grip. Triathlestrong would have to be some combination of both.
Swim with a Sandbag series up the beach. Bike with Deadlift for reps. Then a three attempt max Log Press. 5k run with an Arm Over Arm Pull to finish.
That’s crazy but stays within the confines of the two sports.