All outlets and all electric heaters are limited to 1500 watts max. Also most heaters have 3 different heat settings, like 500/1000/1500 watts. I do try to avoid the max setting especially when we are away from the trailer. I use oil filled heaters because they are quiet and they have a steady heat output even though the heating element switches on and off. Finally, I plug them into WIN100 controllers, these have a real thermostat and temp sensor and are much better at maintaining the set temperature. I can leave the heater on when I leave the trailer in the morning and they will shut it off completely as the day warms up.
I don't fully trust what has been used for wire in these trailers. I had an outlet in the back that I used for an electric heater. I could never run the heater on high. It would shut down after running for a very short time.
This year I ran a new (12-2-G) wire to a new outlet. Now I can run a heater on high with no problems.
2008 Cruiser CF26RK
2013 Ford Eco-Boost
Heavy duty payload - Max tow