Some guys scrape the Mylar with a razor blade to thin it out so it will take the compound curves better. Although I've never bagged a wing with Mylar, I have bagged with peel ply many times. What I would do is end the Mylar short of the tip and run peel ply at the tip. After bagging I would sand and prep the tip for paint and either blend in the same color as the rest of the wing or come up with a color scheme that has the tips painted a different color.