So you bought a 3/4 ton truck with perhaps a 2,500 pound cargo rating, and plan on buying a fifth wheel soon. Installing a 200 pound hitch, then add 300 pounds of passengers and haul a fifth wheel less than 10,000 pounds with a 2,000 pound hitch weight all over the country. I guess it will be one of those super light 27 foot long models?
You might be overweight from the get go.
Then plan on driving on ice up to Spokane?
I guess you are used to driving on salted down roads, that are somewhat level, and not covered with black ice due to all the salt use. However out west, we do not use nearly as much salt.
Going north on I5 can be easy, you can wait out any storms, and just travel a day or two later once the roads are cleared. But once in Washington, if you need to be there say on the 20th, you will need to drive on no matter what. ..
There are only major passes over the 'grapvine' just north of Los Angeles at around 6,500' elevation. It rarely snows there, but there is highway 14/58 through Mohave to Bakersfield to bypass that around 3,500' elevation.
Northern California to the Oregon border is another pass, around 5,000', that can be snowed in for a day or two, but most likely will be open. Leaving Grants Pass is a triple set of hills, only about 1,500' climb each, and then it is basically a valley all the way to Portland OR>
I just worry about the cargo weight capacity of your 3/4 ton truck. If you will have a 3,000+ pound cargo rating, you should be OK - depending on the trailer you picked out. . Needless to say, a 3500 pickup would have been my pick for towing a fifth wheel that tends to have 2,500 - 3000 pound pin weight, 200 pound hitch, and 300 - 500 pounds additional passengers and cargo in the cab.
Have fun camping!
Fred.