Ok so I was outside a little while ago trying to get tail shots when my battery died lol. I have to wait an hour before that thing recharges.

This is frustrating but fun too so I'm going to keep trying.
After the battery died I discovered that if I hold Scooter up in the air head first just like in the book I am looking at now then he/she tends to loosen that tail & I can get a grip on it. That cloaca sure does look pretty far away from the plastron to me. If I were looking at a box or a painted I say this is a boy.

The book.. do you have Pritchard's Encyclopedia of Turtles?
On page 521 there is a photo of 2 muds one is spooneri & one flavescens. The one who's plastron is showing has a tail that looks just like Scooter's. Boy or girl? I dunno it doesn't say in the caption!!
I'll keep trying on the photos unless you have the book & can tell what that is.
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PHRatz