Originally Posted by gsa103

Aluminum is probably the most likely material to fail under the conditions you're talking about. Large strong rider + trailer = lots of force and frame flex. Aluminum also suffers from metal fatigue if its repeatedly flexed, meaning it will eventually break. Carbon fiber and steel both have an elastic limit, where they can repeatedly flex without any damage.

The average rider won't usually stress a frame enough to fracture it, but it sounds like you're riding harder than average especially including the trailer. The new carbon fiber frame will probably be fine. The trailer will likely break either frame eventually, but you can hope that your toddler out grows the trailer before that happens. A steel "touring" frame would be designed to handle much larger loads, but I wouldn't worry about until you break your current steel frame again.