Another WD question

Hello,
I Just bought a 3023 from a Texas dealer this weekend. They sold huskie WDs and that is what they set up for me. I was concerned because they looked confused during the set-up and it took over 3 hrs to get it right. I say that losely because I watched what they did and it did not match up with what the directions said to do. They did everything by eye and my truck dropped more then the 1/2 inch when the system is hooked up. They didn't take any measurements or anything. I am going to set the hitch up this week the right way using the directions provided. My question is they sold me a hitch according label on the bar that will support 801 to 1200lbs TW. The 3023 has a 409lb TW. Is this hitch too stout for my configuration? Will it be safe to tow with this WD? My TV is a 2007 Trailblazer so I need everything set up correctly. Is too much a bad thing? I need to know because I am going up to Raton pass to camp this weekend and I don't want any trouble in the mountains. It towed fine all the way back to NM but it was pretty flat. Let me know. Thanks!

Eric Stone