I don't agree at all with the notion that a 1/2 ton is better, when you're pushing the limits. As I've already said pushing the limits is never a good idea. You want to pull a 5K or 6K trailer, then enjoy the 1/2 ton. If you're pulling the 8K trailer, then your TV needs to increase in size.
Get the bigger truck and be safer...if not for you, then for others on the road.
To the poster who talked about the semis falling behind on the hills...they do that because they don't want to dump the fuel it takes to keep speed, and to also stay safe coming down the hill. It is most certainly not for a lack power.