Reserving space for advert banners on Android

On Android, does anyone know of a tidy way to reserve x-amount of space at the bottom of the screen for advert banners? Preferably implemented in the extended class, so there’s no need to modify SDLActivity.java.

So in effect, from the perspective of the SDL app, the screen height is reduced.

I haven’t a clue what I’m doing with java / Android, so everything I’ve tried breaks it. I was hoping it would be something easy, like mSurface.setLayoutParams(new LayoutParams(w, h-10));

I have a feeling this should be really easy. Maybe something to do with adding another child to the RelativeLayout?