In watermelon I can tell from this side. But I'm not familiar enough with cantaloupe to be sure looking at this end.

No, that's not a real fruit on the right under the female flower. It's a proto-fruit. Yeah, there must be some real biological term for that thing, but proto-fruit is what everyone calls them. That proto-fruit isn't yet fertilized, so it isn't a real unripe fruit yet. If it doesn't get fertilized, it'll dry up and fall off. Not sure if my four female blossoms got fertilized. We'll see in a few days.

A way to tell from the front (and I admit it's much easier on the large squash flowers than on the small melon/cucumber flowers) is if there is a single anther (for males) or the multi-lobed stigma (females)

One advantage of identifying the sex of the flower from the rear is that you can tell before it opens. I do hand pollination of squash and melons, and I look for (in my general experience, the rarer) female flowers before they bloom, so I can anticipate doing that pollination. As in, OK, looks like tomorrow that flower will be opening ... ready, set ...

Rodney

In my experience, male flowers ALWAYS vastly outnumber female flowers. Especially in cantaloupes. For squash, the female flowers are a little more common. I have just been noticing that my fall butternuts are popping out a lot more female flowers than they did in the spring. About a third. It used to be about a tenth.

If you are in 7a, you're not going to have much time for your fertilized melon to mature once you get one. Just sayin' ... After my spring crop matured in the summer, I now have some golfball sized fruit, and I'm hoping they'll make it to the end before the first freeze.

Sounds like you won't have any trouble with frost. Oh, but if it's not outside, you won't have anyone doing pollination for you. So it's especially important to be able to identify male and female flowers. You need to get out your bee costume, start inspecting flowers, and take responsibility for pollination. Unlike tomatoes, peppers, and eggplants, melons are NOT self-pollinating.

I'm thinking that when you do actually get a female flower, the difference will be conspicuous. But if you don't have any yet, you're just trying to magnify details in the male flowers.

Look, if you think you have a female flower, then just pollinate it!

I found a pic of a female melon flower on the internet. I added the arrow to show where the flower ends and the small fruit begins. There is a very definite junction there.

Rodney

I still can't find any open female flowers on my plants! One or two are now closed, and several others are done with, a few of which maybe have melons. Loads of male flowers. Sheesh.