No problem. Implemented and will be in next version. I was asked multiple times for this feature. Before it was not possible to do so easily, but meanwhile were rewritten various parts of code and now it was not big deal.
Now it will work this way : Landscape and portrait modes are independent and you will be able set custom size and position independently. For example : In landscape can be game stretched on full screen and in portrait mode can be applied custom width/height and positioned in middle or anywhere you want.
Is it what you need?