Hi friends, I need help. I have a wedding cake coming up and the bride wants just a very smooth, plain 2 tier cake with buttercream icing. 

She wants nothing on it. I've always used a crusting American buttercream, when we could get Sweetex. I've been experimenting with Swiss meringue and although the taste is fantastic, it seems a little fragile and soft for GA weather. This is a very sophisticated bride and I want something nice that's not overly sweet but will hold up well, and be smooth, she's fine with icing being a little off white or ivory. I've looked at a ton of recipes on CC  and I'm overwhelmed. The wedding is in 2 wks and I don't have a lot of time...I'm wondering what other CC people are doing without our high ratio? ..I would appreciate ANY advice.  Thanks in advance! 

Have you considered white chocolate ganache?  It is, of course, a creamy pale yellow color, but it is delicious and sturdy.

I highly suggest you use this recipe:   https://www.cakecentral.com/recipe/22469/2-icing   I feel it meets your requirements and should be good for your weather situation.