I figured this would be a bad idea because of things like moisture/rain in the doors. But, it would make things much easier to place them there. I figured I could make a water proof casing to suround them. would they get to hot if wrapped up. I need some ideas here. If there is any possible safe way to do this please help.
Are you talking passive or variable/electronic crosovers?
Passive crossovers are simple components usually 2-3 components ea. I have installed them in doors and have not had any problems. I usually tape the ends so that they dont short with the other components. Make sure that you keep them close together.
Electronic/variable crossovers are usually installed before the amp and may be as large as a head unit. I hope you werent talking about this type.