Expired question
V+ 기만 아니면 as past sentence?

Hello, italki users! I hope it's okay that I flood this website with very specific little problems :))

Today I learned the structure "V+ 기만 아니면" ("If only V") from a book.

An example: "덜 먹기만 아니면 좋을 거예요." (If only I ate less, it would be good.")

Now I wonder how to form a past sentence like "If only I had eaten less, it would have been good."

Do I say it like this:
"덜 먹기만 아니면 좋았을 거예요"
or must I also change the 먹기만 to
"덜 먹기만 아니었면 좋았을 거예요"??


Thanks so much for any tipps!!

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Thanks SO MUCH!! :)