I think the THH has a third motor driving the rear wheels. The GM 2-mode hybrids have two full planetary-gear sets with clutches that can change their mode of operation. Both these systems can pull higher loads. I suspect that the TCH system has a possibility of electrical and/or mechanical overload, and subsequent failure, if the car itself is fully loaded and on top of that a trailer is also being towed. If the car is lightly loaded, I'd guess that a modest trailer would be okay. But you would likely have problems if warranty repairs are needed on the hybrid transaxle or on the inverter/converter/HV-battery system.

Stan