The right Goby

I'm not a goby expert but I know there are two types of bumblebee goby. One is completely freshwater (they are distinguishable by stripe differences) and I think they're great fish. They eat any frozen brine shrimp I give them baby or grown (if that's what you meant by prepared versus live).

I don't know a lot about gobies at all so they could be completely different than what you're looking for. They're super small too

My Rhinogobius rubromaculatus seem much less picky about the temp than my duospilus. Really, really great fish.

And desert gobies really aren't seasonal. yes, they're short-lived, but I think they can reach 2 years. Also, they breed super easily and are very peaceful, so you can get a colony going long-term. Great fish.

And, of course, you could go stiphodons, but they're a little fussier.

also, have you thought about darters at all?

I think the hardier darters like johnny darters or swamp darters would be fine, but you'd want to confirm on nanfa.

The fish you're looking at are subtropical, but they live in areas that do get plenty warm in the summers, even rhinogobius duospilus. In the end, it's high oxygenation they need, not cool temperatures, though it can be harder to maintain high oxygen in warmer temps.
My rhinogobius tank gets into the lower 80's at times (though usually it's around 78 in the warm months), but it's overfiltered with a canister that keeps the top of the water moving at all times. The fish do really well, even show breeding behavior at these temps, although my only successful breeding thus far occurred at lower temps. I have read of duospilus breeding at 78, though, and my duospilus fry were raised at 78.

Of course, all my evidence is anecdotal in nature, so I can't make any guarantees.