Not difficult at all. From New Westminster, it is about 7 hours at a leasure pace. Sasquatch set up is not like Pemberton, you camp with your car, so depending on when you arrive, the only think you may face is a bit of a line-up (we usually arrive on friday late afternoon and the longer wait time has been 5 minutes).
Do not go through New West or Kamloops. From Kelowna go south through Penticton to the border crossing at Osoyoos. From there it's a straight shot to George, WA. It should only take about 6ish hours. Super easy!!