I think the trick to this is not to be TOO good at it.
Seriously though, everytime a guest walks away disgruntled, you lose a little bit of your "fruit meter". So if you strike a balance between keeping enough people happy (so that it doesn't empty completely and end your game) and keeping enough people unhappy so that you never level up, you can literally play forever. I've been experimenting, and level three or four seem to be good levels to stay at. You can just keep racking up points, VEEEERY SLOOOOOOWLY, all night if you maintain that balance carefully.
That said, it would take FOREVER to get a gold trophy this way. But it is possible!
Edit: Oh, Yeah. You also have to keep the rotation at the counter moving enough so that you don't have too many people in line. The easiest way to do that is just to always serve the people that have the MOST hearts, since the others will give up and leave an empty counter seat which you can then fill with more people you are probably not going to serve. Yay for bad customer service! LOL