RE: Where to put CG on a flying wing?
I hate to say it but you have a reciepe for disaster. All wing aircraft have to be designed with the proper sweep twist & spanwise lift distribution. If you do not follow the rules when it comes to an all wing you will have your hands full at the contols. The cheapo special foam wings with twin speed 400 engines suffer from awful stall & death spiral characteristics. I have flown several all wings, some with awsome flight qualities & some with awful qualities & I would recomend that you read more about the design architecture of flying wings before you get carried away.
To answer your question about CG location would be impossible. there are to many unknowns. I can tell you that the CG band is very small. A CG to far aft is a crash waiting to happen & a CG forward is a hand full