I have used, out of necessity, a motorized, 120v device called a Powercaster
(Google is helpful here). It works well, but it has limitations: If the slope you are trying to move it on is too steep the tongue wheel may spin on the pavement. This depends on tongue weight
, rain on the pavement, etc.
If conditions are poor I either ask another person to stand on the tongue or I put a large container of water on it before I try to go up a hill. That helps.
If you have a really tricky situation, or if you simply want to astonish fellow campers by having your trailer follow you around and doing fancy maneuvering tricks, Google "Truma" for the European solution. These devices make the regular trailer wheels motorized temporarily and you control the trailer completely by remote control. A really slick, and really expensive way to move a trailer around.