The only time that the turbine housing will be subjected to that much heat, is under boost. either alot of boost, or a some boost for great periods of time.
the trucks will climb a hills with little to no boost depending on the grade of the climb and how much load you may be carring.
I would recommend watching a boost gauge and if you see boost on the uphill climb for long periods of time, pull back on the throttle a bid.
Now the ac line that is closest to the housing has a heat cover supplied in the kit.

 

The reason I am asking, is from what I have experienced in 25+ years with Saab turbos. (used to work as a test driver for 5 years at the factory)

If you drive a Saab on a flat highway at say 85-90 mph for more than 3-4 minutes the turbo is glowing dark red, only visible at night.

My next question was also answered above, the Trick set up is a bad idea for towing a travel trailer. (wich I do with my hoe)

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No you can tow with it, just do not race up hill while towing. I have towed a open car hauler with a car on it, but will admit never looked under the hood in the dark after doing so.
I have seen headers glowing thou, pretty interesting to see, does not hurt anything just interesting.
I think if you keep an eye on egt, boost, engine temp you could tow the same weight as the vehicle is designed to do, the tune has to be right.