I don't know for certain but, I am wondering
if the oils in the zest will kill your head retention. I have heard it is not recommended to add a slice of lemon to a Hefe, as has become popular here in the US, for that very reason. But perhaps that is from the juice and not the citrus oils in the peel?
Sorry I am not offering anything solid advice wise.
Merely speculation, but that was the concern that sprang to mind. Don't want you to be disappointed in your brew.