Plenty of big rigs use that route (logging/timber trucks, wheat/hay trucks, etc.). Doesn’t mean it’s the best option 🙂
If you have concerns, run out 90 west to 395 down to tri-cities area and pick up 84 in Oregon to get down to Boise area. There is a section you will need to run up on 84 (I think it’s called hells canyon or something east of Pendleton). Came down it earlier this year. Was exciting coming down, would be a long grade going up. But the view is amazing.
On a side note, if you find yourself on 84 east of Boise looking for an overnight (or a couple night) spot. Check out Mountain Home RV park (in Mountain Home). BIG pull through spots, VERY wide paved roads, etc. We had no problem getting our 45′ coach + 25′ trailer into the park, through the park and into the spot (with plenty of room in front and behind) and then out again.