Lillian Too and front door locations

[myfs_100871]

Dear Master Lee,
First of all, I'd like to thank you for providing this forum and website. I've read many of your past topics and can't find out why Lillian Too recommend that the excellent location should be the back door and the front door face the opposite (normally prosperity location). Her book agree with everything you say except that the main door is the back door instead of the front door. I would like your opinion on this because I am buying a new home and this is the first step. Thanks again.