Circit breaker pops when trailer plugged into house power

[MrGallegos]

For the past 5 months, I have my TM opened and used as a spare room. The TM is plugged into a power strip/surge protector which is then plugged into an outlet in the garage. The fridge is set to AC and occasionally the guest using the TM plugs in a coffee maker, or hot plate.

The vast majority of time, there is no problem. But once in a while the circuit breaker in the surge protector pops. I then have to go and press the switch on the power strip to reset it and all is fine. This sometimes happen when there is no additional appliance being used, no lights on, no fan, nor anything else but the refrigerator. All would be fine for days, then pop, reset, pop, reset, all is fine, and repeat. Any ideas on a possible solution?

Additional details:
Due to the distance between the outlet and trailer, a 75ft. extension cord is used.