Looking for cuckold pregnancy

I can't give my wife kids. We would present it as a sperm donor situation, as it will be just we'll have lots of fun with the natural insemination method (NI). We've started the process a few times now but it never works out for various reasons, so far. 3 of the guys we started with were black, and I must say the thought of my wife with another black guy turns me on to no end.