Rural PO Hours

Howdy!

I live in a small town where the PO closes at 3:30. Due to scheduling, it would be 100x more convenient if they were open until like 3:45.

I send a decent amount of certifieds. How many do I have to send before I can convince someone at the big PO in the sky to extend their hours, or at least not get laughed at for asking? Does it impact or help them at all? Because with them closing when they do I have to take them to a bigger PO and I'd rather keep as much "business" locally if it matters.

Thanks