Being cross dominant isn't a problem. It's just the way a lot of folks are. It ain't a problem for a surgeon, or a machinist, or a seamstress, or anyone that does close up work where they need to see things clearly. It's not a problem for shooting. With a handgun just turn the head a bit to bring the dominant eye into play. That's it. With a long gun close an eye or learn to see the sights or through the scope with the non dominant eyeball.
Frankly it's more trouble with bi-focals.