Whenever you run RA2YR (or even TS), can you set the resolution of at least 2560x1600?
If so, do you have a resolution option that increases the 2560 width but not the 1600 height?
Does that option work? How far can you widden the resolution without increasing the height of 1600?
Note: Included MO, TI and DTA because they use the TS/YR engine, and so are included in this question. It's a question of engine limits.