Da niente Cara !
As I said, you can just use orange recipes using bitter orange - or, as I do just mix with sweet oranges.
If you like the Grapefruit taste, then you can use them pure.
I like it sweet or sour, but not really bitter.
Just duck orange, for the bitterly duck meat fits perfectly to the bitter orange taste.
By the way, Earl Gray uses the FLOWERS of the Bergamot, not the rind of the fruits, but that will taste also very well.