First thing I would do to limit the food that goes in, to make it easier on your wife and make sure the tank isn't overfed, is take an ice cube tray. Add the right amount of food to the cubes and fill with saltwater. Freeze. When it comes time for feeding, all your wife has to do is pop out a cube and toss it in the tank. The cube slowly melts, releasing the food. I do this for my petsitters and it works great.
As for water changes, my other concern would be evaporation. If you haven't already, let yur wife know she may need to add water. Have pre-mixed water ready at just a slightly lower salinity to account for the rise in salinity in the tank due to evaporation.
Two weeks isn't an excessively long time but I would make sure all of my filter media, if you are using any floss, chemical media etc, is 100% fresh.
You will need to do at least a good 20% change I'd say on the day you get home and maybe another 10% each day over another two days. I would do tests in between just to monitor...your problem would probably be more from nitrates than ammonia.