I'll just throw out there that you should see what you get out of the beer before you go to great lengths to maintain temperatures. While the advice here is all solid, if it turns out you're happy with the beer you can make at a 72°F ambient temperature, then there's no need to worry.
You might also look for yeasts that are happy at higher temperatures. I don't have experience, but I believe hefeweizen is one such example. That's why they're "summer beers." When temperatures drop in the winter, your ambient will quite likely be more appropriate for cooler fermentation. There's nothing wrong with planning your brewing schedule to match the temperatures that Mother Nature provides you with. Some might even consider that to be a desirable thing.