On most toons I normally alternate between 2 sets of gear using a macro to swap to the previous gear. For example I have a toon that swaps between a physical DPS and healer equipment on daily basis.
1) Before it can determine which was your previous gear set you need to check manually which two equipment swaps numbers you are going to use. If you only have 3 equipment swaps then it should be easy to check when you have the character interface open while using the macro. Set the swap to one of numbers you will be using
2) Activate the macro. If it doesn't swap back to one of the correct swap numbers you need to manually set it to one of the two swaps and repeat this step until it memorizes it.
3) Once it's swapping correctly you can exit the game to save it before it crashes.
You can reuse the macro even if the equipment swap numbers change after you restart the client. If you use more than 2 equipment swaps on a frequent basis then there is no easy work around.