4x6 in dash or make custom windshield panel things? (dont know the name)
 

You know those custom gauges they put next to the windshield panels? I want to put mids/tweeters there so it projects outside of the vehicle...

right now I put the tweeter next to the stock mid and it's not only blocked by my leg most of the time, it doesn't project outside the vehicle either!

Is there any high end 4x6's that have a crossover? or a coaxial/2-way that actually sounds decent?

you talking about gauge pods right ?

Why on earth would you want to do that? If it's for party/tailgating purposes then why not build something that you can connect/disconnect for that purpose? I used to know lots of guys who used to do that with those pre-built 6x9 boxes. They'd hook them up and lay them on the top of the hood, or top of the trunk and jam away. Easier, cheaper, sounds better and will potentially get louder than anything you could do with the 4x6's. One guy went so far as to use molex connectors to make hooking it up way easier and to unhook the ones in the factory locations to make the load right on the HU. Besides, you couldn't hear them in the truck from the outside anyway.