Do your thing. Im telling you, you wont even hear them in the trunk. The 2000-20,000Hz frequencies arent going to penetrate your seats/rear deck. But I say find out for yourself, this will be a good learning experience for you.
Oh they sure will. Imagine...you have a 1" hole in your tire. You plug that hole with a 1" speaker. You think your tire will hold air? Kind of a dramatic example, but speakers are designed to let air through.The tweeters wouldn't cause any seal issues.. They are surrounded by like a big ceramic cone.plus I would seal with that caulk type stuff also