The Otos should be fine, but the CPD's won't be happy and I'm not shrimp guy.
What else is taking the water from 78 in the room to somewhere in the 80's?
The fan lksnrinker posted above isn't really huge, but if you go to a dollar store, you can find a really cheap desktop clip-on that's really small enough to match the size of the tank.
You may not be pleased with what eggcrate will do to your lighting. They are meant to be within a couple of inches from a T5 tube that's 8 to 10 feet off the ground and focus the light straight down. So that in an aquarium where you want light dispersion over the tank's footprint, you'll notice the tank looks a bit dimmer and the edges will actually be light-deprived. Additionally, if any of the fish you have in there want to bolt, it won't stop them.
If you think the problem will persist, your best bet is a couple of layers of pond netting. At least two layers with the mesh over lapping. It's UV resistant, and won't block or affect any lighting meant for the tank, and you can still get a little desk fan and aim it at the water surface. Stepping up water movement will also help the cause immensely. Lastly, remember to compensate for higher evaporation rates.
"Why can't my wife see all of this stuff as an investment?"