Well, its not the best path. I have not tried these 8 slot megatrailers after a short test any more as these make very little sense in my opinion (high center by length every now and then). A 2x4 cargo setup is way more flexible and even faster. If really needed - take two of these and they can support each other.
Edit: What I really "need" - Gooseneck 6 slot high saddle semi offroad with some ground clearance. So you don't get highcentered and caught at the first wannabe-hilltop. A lighter 4 slot gooseneck saddle low offroad trailer would be also nice.
Regarding your route selection: From your map's point of view, the northern offroad path to the factory along that "river" works way better. A lot up and down, but no mud and the bank angles are ok.
The problem with heavy trucks and heavy trailers - you have six wheels to get them moved for 30 tons plus as weight. And you need thus a lot of force, so "power itself" is completely irrelevant as long as you lack the traction to make the power move something.
Edit: I did that "from the crafting site for pipes to paper factory" job with a stock 5070A (4 or 5 slot Semi trailer setup), the White Western (also as a semi hauler) and the 2070A with flatbed. Worked nice enough uphill and then parallel to the river just in front of the bridge, then right to factory. A bit boring by the number of cargos, but it worked. And if you take different trucks for each repetitive one, its less boring.