Actually, I don't think it makes sense to add a splash screen to this particular project as it's going to be open source and therefore easily removable (or even worse - customized).
I thought of adding a lot of checks and countermeasures in FtFtBT DX to make sure the splash screen's integrity is maintained, but I concluded that it would be a waste of time. On the one hand, anybody willing to spend whatever a repro cart costs know what they are buying, on the other if you really want to remove it, you can remove it. I suppose the repro stuff is inevitable.