Unfortunately, no, there is no way to re-name the photos on the iPad (or while e-mailing them). But, when I put photos into an e-mail, they are labeled photo1 and photo2. Then, when I open the e-mail on my PC, that is how they are labeled (and downloaded). So, of you select them in order from the Photos app (the most recent picture is the last), they'd be in (1) in the order you selected them in the e-mail and (2) in order from taking them on the iPad.
Regardless, he good news is that the iPad puts metadata on the pictures (for want of a better term). So, after you get the photos to a computer, you can look at the properties and see the date and time for when the pictures were taken.
That's the best I can do for good news. Sorry.
Marilyn