I have found better creme at gordon food services (GFS) although haven't used yet. Another option that tastes lighter than buttercream and that can hold up in the heat is Hi ratio frosting. I think "sweetex" is a brand name. You need to use HI ratio, not standard shortening like crisco. I am including a recipe below. If you are using for a filling or under fondant, I prefer to use only 2lbs powdered sugar. It will still pipe well (I've used many times for cupcakes), but won't crust as much.
Fluffy Vanilla Buttercream using all Hi Ratio shortening
2 cups (386 g) high ratio shortening
2 Tablespoons (24 g) clear vanilla extract
1/2 teaspoon (2 g) butter flavoring
1/2 teaspoon (2 g) lemon or almond flavoring
4 lbs. (1820 g) confectioners’ sugar
1 cup (238 g) or more if needed – milk or heavy cream (you get a softer crust using heavy cream)
1/2 to 1 teaspoon (2g to 4g ) salt (This will cut the sweetness.
Cream the shortening and flavorings . Add the confectioners’ sugar and cream, mixing slowing and gradually increasing speed . Mix approx. 8 min. until creamy and smooth, DURING THE LAST 2 TO 3 MINUTES OF MIXING SLOW DOWN THE SPEED TO VERY SLOW THIS WILL ELIMINATE MOST OF THE AIR BUBBLES THAT OCCUR. If you are still seeing what looks like bubbles that have burst (small circles) in your buttercream, continue to add milk a teaspoon at a time until most of them disappear.
This is still sweet though the salt cuts some of the sweetness.
Makes appproximately 11 1/2 cups