What Joed32 (no relation) is correct.
But..........don't ya hate the buts?
The bucket will be a problem except in a perfect world. If it is bumped even a little the weight of the AT9 (5LNB) dish will move it, as will just a little wind. You have to re point it. Do you own a Birddog? What you want is called a non penetrating roof mount with a 2" mast. This thing arrives and you assemble it. Then you put several cinder blocks or sand bags on it; works great. Google "DTV accessories."
The other "but" is getting the cable into your unit. If you are OK with the tech using drills there is no problem...but.....if drills are a deal breaker you end up with flat coax to cross a window or door. They are fragile and many won't use them because of the problems.
Finally, diplexers should work but don't. In theory you should be able to use the same cable for both the sat line and the CATV feed but it has been discovered that the internet service is interrupted. Maybe an AB switch will work.
Aside from that, all is well.
Go for it.
Joe