I prefer live shows in the shower. But I think there are plenty of water resistant solutions. They put speakers in boats after all.
I personally prefer the open door aimed speaker method. Just make sure never to use a toaster in the shower as the repercussions are pretty painful.
I suggest a different brand than blose. They tend to be way overpriced.
JBL Marine Series MS9200. JBLs come from a good speaker company that is known for their driver quality. I suggest you look into JBL/Infinity products instead of Blose. You can get them much cheaper and they will sound better.
There are plenty of Boss and JBL dashes as well.