We have made a round trip of the USA 5 times and actually are in the process again, presently in NM. Normally we go west across the northern third of the country and cross the rockies in MT.
We have taken both the Interstate across the northern third of the country and Route 2. The Interstate is never a problem because there is not that much traffic and people can always pass you. We never drive over 60 and are never holding up other people.
Route 2 was not an issue either as regards to traffic, we just pull over to let people who are working pass, they always appreciate it.
One of the big issues is head winds, particularly in the Dakotas; today in NM it's gusting to 80 mph. We went to a restuarant for lunch and could barelyopen the door to get out.
We do carry the Mountain Road Directory with us and use it when we're not on Interstates to be forwarned of dangerous sections. It's never the uphill sections that are a concern but rather the down hill sections. You do not want to toast your trucks brakes. We plan ahead and tend to down shift for long hills even though our trailer has brakes.
As to going up the big mountains, we tow a Scamp 16 with a 4 cylinder Honda CRV, we've never had a problem.. Though the mountains are tall, you usually start off at at least 5,000 feet, for example once you reach the NE/CO border you're at that elevation and everything looks flat.
As well road builders do not try to take you over the highest peaks, they arre looking to make the lowest, easiest road possible.
As to holding up traffic, on Interstates you wont because of the multiple lanes and the typical 18 wheeler is not charging up these Mountains either.
As to coastal hairpins we have driven the WA, OR and CA coasts without issue. It is a beautiful road. Thlough we generally drive it in the spring or fall
, they have a lot of pull overs to let others pass.
My general rule is to take it easy, be courteous to other drivers and most importantly stop often to enjoy the sites, the west coast ride is beautiful.
Additionally, I will say we've towed on a lot more severe terrain the a drive across the country with our Honda towing one of our trailers and have always managed to make it without incident.
I don't think you said when you're going, a factor, or if your truck is a standard or automatic or if you have a transmission cooler if it's an automatic.
Wishing you the best of times.