Can the Indydebi's Crisco-Based Buttercream Icing recipe be tweaked for flavors such as vanilla bean, white chocolate and peanut butter and still withstand the HUMIDITY? I have a wedding taht i am doing this weekend and the humidity is high and the even will be outside. Any help or suggestions??

in my experience peanut butter can get funky in icing -- add in the heat, idk -- i would not do a white chocolate icing for an outdoor wedding --

i added a quarter cup wondra flour in my american buttercream to help it withstand humidity --

but i discouraged outdoor wedding receptions -- rarely had to do them -- i advised that you lose half the bang of your cake -- that it's the focal point of the reception and if you can't set it out to be enjoyed -- what's the point -- 

hope it all works out for you

As K8 said, the only change I would be concerned about is the use of PB.  Otherwise I have found unless it is very humid, ABC dries out rather than melts in high heat.  Adding vanilla bean seeds or white choco should not effect the outcome at all.