My understanding from having used C a lot is that taking it on an empty stomach gives you better plasma distribution of the drug initially. After you have that established, it doesn’t matter much what you eat or when. You still will have the same half-life performance period, which for you is very good.
The track record of this and similar drugs shows that older men (which you are not) get longer-lasting effects - in spite of the stated half-life - than younger men because older men have slower metabolisms. I get usually a pretty reliable 72 hours. Because I do have ED and I know enough about why I have it, I pop 20 mg of C every third day. Keeps me very even, performance wise, during that time period.
You are fortunate to have that long a response. Saves you money.