You didn't ask, but indydebi has an all-crisco crusting buttercream recipe that holds up VERY well in extreme heat. Check it out. It is a favorite on this site. Good...
Hard for me to describe, but it definitely isn't soupy. Quite soft, softer than a Regular BC, but not as soft as a whipped icing. You can pipe well with it though I have never made flowers with it. And of course, smoothing takes a bit...
When I don't need a crusting bc, I use WBH House buttercream exclusively. It is the best! That being said, I have never had any problem and am sorry you did. I hope someone can give you an idea as to what happened.
Ahhhh, I guess that makes sense. Cute idea though! Can't wait to see a picture when you're done. Good luck! BTW, I just looked at your gallery. You do some amazing work!