For most people, "wherever you want" is going to be with the outside edges a bit wider than your shoulders and vaguely parallel to a little diagonal. That's not possible with really any pair of full keyboards I've ever had.
I just moved them around until it was comfortable; it ended up with them being a bit further apart than shoulder width, the keyboards certainly weren't close to bumping into each other even though they were standard garbage 101 key USB business keyboards; I think they end up about a foot apart at the closest. Give it a try.
Space them vertically. The left one to the top, giving you a space on the right for the mouse. Or the right one to the to top, then your mouse would be under it.