Is TMPGEnc DVD author useless for backups?

I have yet to get TMPGEnc DVD author to work. I was trying to add a chapter menu to a main movie title that I had re-authored with Shrink 3b5. I always get an error message when I begin the output that the combined bitrate is too high, yet TMPGEnc gives me no solution other than to ignore, and that the results will be a non-standard DVD that may not play...which I don't want. So how do I lower the bitrate?
Has anyone ever used this program for backing up a DVD? I have read the avalible guides. I also know that Shrink3b5 doesn't work with the output side of TMPGEnc like 2.3 did, so I compressed before attempting to use TMPGEnc.

Best wishes,
Frank