Your Mack needs a lot work yet Steve before it could climb that spiral, starting with better tires with thicker sidewalls, and much much lower reduction to keep the spd constant so you don't jerk the load off, there's an 8' stretch on the 1st incline that's 14*!
How tall is it anway? The Mammoth fits through the window. I'd probably have to widen the entire roadway 8" for you and double the width in the corners. The Mammoth only has an inch or so side to side & 4 or 5 back ups to make each corner.
Using a 20L bucket (5.2us ga) for a volume measurement, what's the mack hold?
Each tandem trk & bd trl is about 4.5L and a 27" semi trl is about 7L.