Hellobee Boards

I haven't tried this one yet, but it comes highly recommended.
http://www.canyoustayfordinner.com/2010/12/28/the-best-whipped-frosting/

I use recipes from the Magnolia bakery cookbook (there are two, I have the second one). They aren't super duper sweet, but still use plenty of confectioners sugar. My favorites are their chocolate one and lemon, both are pretty thick and would hold piping, but they are very butter heavy. I can find the recipes online somewhere if those sound good.

@lemondrop: coconut cream frosting meltttttttssssssssssssss. At least it did for me.

http://www.cookingclassy.com/2013/05/banana-cake-with-whipped-cream-cheese-frosting/

i liked that frosting for my LO's cake --- it's light because of the whipped cream, but crazy delish because of the cream cheese.

the trick to having it NOT melt and to keep definition is..... using Nutriwhip (blue box in the dairy aisle beside the heavy cream). It's totally processed and probably 90% synthetic, but it works and tastes fine, especially when mixed with icing. It is also already lightly sweetened, so you won't want to add sugar to it, like you would regular whipped/heavy cream.

In order to get it more pipe-able i would use considerably less whipcream/nutriwhip to icing ratio than the recipe indicates.

anyway, this is for a lighter feeling/tasting topping --- if you want to go more traditional, i'd just go for a regular icing that would pipe well, be more sweet probably, but also be relatively stable in the heat