The zip code deal will basically tell you what compass/elevation setting to point your dish, but you still have to "find" the satellite through the trees. You could watch the signal strength meter built into the receiver, but that is not always convenient. I found a zip code/azmuth (sp?) setting list on the internet that I keep in the trailer, but the list built into your receiver should work fine. I use CW finder and strength meter (cheap models), they both worked out good for me.
However, I could not get it to work through the existing "cable" connection on the TT. I ran it through a storage compartment door, but it was ugly. Is the signal booster jack screwing up the Satellite signal?? This jack also extends the outside jack to the bedroom. I had a TV fall off and rip the jack out once (something you only let happen once), could I have wired it back together wrong? It seems like the kind of thing that will either work or not, and it works fine with a cable connection.