As others have pointed out, you'll need to use your gears, all of them. No matter what TV you have, being at the upper limits of towing capacity means you are going to be one of the slowest vehicles on the road. Make no attempt to keep up with everyone else. And do not be surprised that your non-turbo motor is especially slow climbing at altitude. At 10,000 feet, your engine will produce 20% less power than it does at sea level, so expect it to struggle more than usual. Go as slow as you need to. Stay in the right lane, you will have plenty of company.