From what I know (and believe me, I am a cake-a-holic and a buttercream-a-philic, so I paid close attention) from discussions with my baker for my wedding cake…
You can choose to do a purely butter buttercream. The issue is temperature, as someone already pointed out. If this is an outdoor wedding in Boca Raton in August, you will probably regret it. If it’s an indoor reception and you can transport the layers with minimal exposure to heat, you’ll probably be fine (and you’ll have a little more transport time if you frost and chill overnight). As a sort of test, ask yourself if a hershey bar would stay nice and crisp in the location…
If you’re not sure if buttercream will hold up, you can do a 50/50 crisco and butter… (the hershey bar bends a little before it breaks)
And if the reception will definitely be in a hot location (the hershey bar goes “squoosh” when you pick it up), then you probably will have to consider a solid-at-room-temperature fat like crisco. Just one dose of saturated fat won’t hurt anyone (but it doesn’t taste as good as butter).
As for boiled frosting-- it caught my eye that you didn’t like a “shiny” frosting and in my experience, boiled frosting can be a leetle shiny.
