Wow, formal AND pastel colors attire. A little too imposing on the guests IMO. Some may prefer not to attend because of such requirements. But anyway, back to topic...

Combining formal and pastel color, well, it doesn't look like it's that formal anymore. You may be able to get away with the Clooney no-tie look , if you can pull it off (medium to light grey suit with pink buttoned shirt underneath?) Also, wearing a simple blazer is also a whole lotta better than the jacket-less long-sleeve with tie look.

Oh, and if you are going to go with a long-sleeve barong, please be sure to wear long-sleeve undershirts as well.