Yours is probably the safest approach since it delivers a version for each resolution, but probably works multiply. Another choice is to use a liquid layout to match different sizes, that means use the Stage.onResize listener to allocate your stuff around the screen. If you design with this in mind probably you can achieve the same goals with less effort
Another thing: use Stage.widyh or height instead of screenResolutionY and screenResolutionX, since the browser can not be in full size (but usually does) Also don't check for exactly sizes but for ranges, since lately there are a lot of new devices with less standard screen sizes. My laptop right now has 1366 x 768
Jorge