There are bibs and there are bibs. I have a pair of summer weight Gore Bike Wear bibs that are very low cut front and back and the material up top is quite sheer. They're so light, you literally don't know you're wearing bibs, no matter how hot it is.

With the low cut, #1 is no problem in the bathroom (If you're having trouble with the other, you might want to consider getting up a half hour earlier for that first espresso...)