Hwy 3 (B.C.) Hope to Penticton

No problem. Do it.

You should have no problems with your length. I travel that route with an overall length of 47 ft. Last fall they were straightening some of the road so you will likely come upon some construction.

I do it every June with the rig in my signature and used to do it with my 2001 CTD auto with no exhaust brake and a 10K fiver before that.

Until the Coquihalla was built in the late eighties it was the only route to the southern interior. It has some pretty good grades and twisty bits but vehicle length is not a factor. 18 wheelers use it all the time.

No worse than HWY 20 from Sedro Wooley to Twisp IMO. Done that several times as well.

Yup no worries.... With my rig I'm over 52ft. Also there are many many semi trucks tha drive that road every day ( mostly night) a great road no issues.
There is a long hill ( down hill) on the Princeton end coming down towards the mine.
Use lowest gear put on your 4 way flashers on and use your breaks to keep your speed in check, and you will have no issues.
Soup.

Living in Princeton I have driven the highway many times.Not much happening once you pass the slide area thru the park. After that it gets a little more curvy and hilly. There will probably still be some construction near the Princeton end. Princeton to Penticton to is a piece of cake.

Watch some of the curves, they can be tighter than you're used to and believe me, you will want to stay on the road. There's a long downhill into Princeton, the road is newer there, and wide, but take it easy and you'll be okay.

Nothing serious. Road is the same as most other roads in BC.
Done that many times with 5th wheel and with a motorhome.

just take your time and enjoy the drive. Lot of hair pin corners and a few long climbs.