The outlets/wiring in my storage bldg are 20A. The 20A circuits consist of #12 wire and 20A rated outlets. Most home wiring is #14(smaller gage) with 15A rated outlets. I just use a 30A to 15/20A adapter to plug in.
Park the trailer close enough so you don't use an extension cord. A longer/smaller extension cord will create voltage drop and increase the current draw thus tripping a 15A breaker. Also, if the outlet you are plugging into is too far away from the breaker panel, there will be increased voltage drop.