Towed the new TT home

Go as fast or slow as you want, but keep in mind that low RPMs are not your friend. Gasoline engines need to rev in order to create power. At low RPMs you're forcing the vehicle to drag the load up the incline using little power (lugging) which is very stressful for it. Your engine will make peak HP around 5000 RPM. Seems counter intuitive, but keep the RPMs high to stress the engine less. Some people don't like the sound of screaming engines while going uphill, that's where diesels shine. They make their power at much lower RPMs so you can easily cruise up at 1800 RPM.