20-Gallon Tank To Be Located Next To Exterior Door

[Aquarium]

First of all--I'll say that I know this is not supposed to be done--drafts, etc. I know. But does anyone have any recomendations for making this work? I know the best thing to do would be to keep fish that don't mind temp fluctations--but I really do want to keep a Bolivian Ram (or 2). I was thinking I could rig up some sort of insulation blanket to put on it when it's very cold outside and the door will be opening/closing a lot. We live in the southeastern U.S., so very cold weather is unusual. It's the door to our back screened-in porch. (It is currently a frequently used door, but the front door would be just as easy to use for going to the cars if we had some pavers leading to the driveway...so we could cut down on it's usage significantly). I may be confused about the physics of it all, but it seems the draft would need to be fairly cold and sustained for it to affect the temperature of 20 gallons of water contained within glass walls with a running heater...

Thanks for any and all help!

 

[KittyKat]

But does anyone have any recomendations for making this work?

Yes, go coolwater, not tropical. South US? Maybe even go for small native fish so the tank is unheated or with minimal heating anyway! TropicalFishHobbyist had a good article on some in the last or current issue.
Think along the lines of hillstream loaches, white cloud mountain minnows or paradise fish if you want coolwater.

I know the best thing to do would be to keep fish that don't mind temp fluctations--but I really do want to keep a Bolivian Ram (or 2).

In my honest opinion, you want at least a 3ft tank for Bolivian rams and starting at 40 gallons.

I was thinking I could rig up some sort of insulation blanket to put on it when it's very cold outside and the door will be opening/closing a lot. We live in the southeastern U.S., so very cold weather is unusual. It's the door to our back screened-in porch. (It is currently a frequently used door, but the front door would be just as easy to use for going to the cars if we had some pavers leading to the driveway...so we could cut down on it's usage significantly). I may be confused about the physics of it all, but it seems the draft would need to be fairly cold and sustained for it to affect the temperature of 20 gallons of water contained within glass walls with a running heater...

If there is reason enough for you to worry about it, I think you shouldn't go for tropical..

 

[Aquarium]

Thanks for the advice...thinking maybe subtropical...it would save money, too... (though I was loving the idea of having fish with such personality like the Bolivian Rams have)...have created a new post asking for ideas with the subtropical fish I like.