Hummm, think I may try this Swiss meringue buttercream with powdered sugar and shortening
I found this on Craftsy and it's called modern buttercream with Joshua and Joshua is somebody I guess from the Food Network, it's a free class so I might try to add the link if anyone is interested. In the class he notes that the addition of powdered sugar adds stability and subbing out some of the butter for shortening and hopefully high ratio shortening which I have will help with warmer climates. Seems like the taste may be better than straight up American buttercream. So here's the recipe
Ingredients
8 egg whites (about 1 cup) 1 cup granulated sugar
6 sticks unsalted butter (3 cups), at room temperature
1 cup confectioner’s sugar (sifted) Pinch salt
2 tablespoons vanilla extract
Directions
Over a double boiler, heat the whites and granulated sugar and salt, whisking constantly, until all the sugar is dissolved. Heat this slowly!! You don’t want scrambled eggs!
Place the mixture in a stand mixer and whip on high until a peak forms and the mixture is cool, about 5 minutes.
Turn the mixer to medium speed and add the softened butter a little at a time. Remember, depending on your area, you may need more or less butter.
Add the powdered sugar and vanilla and mix.
Tip: In warmer climates/seasons you will want to change the amount of butter to 4 sticks (2 cups) and also add 11⁄2 cups of vegetable shortening to the buttercream. This will give more stability when the weather is hot.
https://www.craftsy.com/cake-decorating/classes/modern-buttercream/35441