Yeah, I could get behind that. I might suggest calling it N. American Summer Beers. There's nothing wrong with Lawnmower Beers, we all know what it means, but it's too established as a term and covers way too much ground. N. American wheat beers, fruit beers, Hefes, Kolsch, Cream Ale, CAP, the various N. American lagers, Golden Ale, Australian Golden Ale maybe even dry examples of UK Summer Ale, etc, they're all "lawnmower beers." The AHA would need something much more narrow to create a "style."
Spit-balling, "A style of beer designed for consumption during hot summers in N. America, emphasizing dryness and a refreshing quality. The grist is not tightly defined and can be any color, provided it is dry and refreshing. Adjuncts are often used (corn, rice, sugar), but not necessary. Hopping can be variable, bitterness and hop flavor are acceptable, provided that they do not detract from the refreshing, quaffable quality of this style. Yeast selection is also variable, but should emphasize the refreshing and quaffable nature of this style."