having recently completed a 7k trip around BC and Yukon with my 95, 5.7, 3.73's towing about the same weight, relatively quite roads due to time of year, here's my take ...
pretty tough to go slow, you gotta keep up with traffic.
speed limits are just a suggestion, usually 20km's over is the norm, i suspect its worse in the states.
steep hills weren't the issue, cause everyone pretty much has to slow down.
the area where i found it the most stressful, were those long small up hill grades that go on for km's, once you start to lose momentum you're done, especially when speed limit is 110km and you're fighting to keep it at 80 and everyone is doing 130 ...
the other area was having a head wind, especially if it was blowing pretty good, really brutal on the left foot, gas guage and speed.
get used to diesels with a rig 4 times the size of yours cruise by getting about the same fuel mileage and the transport trucks, they haul a$$ .....
i doubt i'll be doing any long hauls down the states with it.
the 95 got a work out for sure, replacing head gasket currently ....
i would try and pick times when things aren't quite as busy for travel if possible.
drive safe.