Never exited by the west side, but entered that way 2x. Once with a Ford Ranger pulling a TrailManor 3023 and again with a 2013 Ford F350 6.7 pulling a 9.5k 30' fiver. Both times we exited I-90 and took 14(?) through Shell Canyon. Theres a great (no hooked) forest service campground by a lake shortly before descending into Sheridan.
Now mountain grades and driving steep, long grades don't bother me. Slow and easy and no problems. We now have a 36' 12k fiver and I'd not hesitate to travel that route again. Keep your equipment in great shape and enjoy.
FWIW, that Ranger was a 4L V6 and had no problems with power up, or down with the 3500+ lb. trailer. And coming down Wolf Creek Pass in CO I lost 1 trailer brake (wire broke at the magnet). Realized it part way down. Took my time and fixed the brake on the side of the road in the next down after purchasing supplies. Sure, I was way more alert, but it was totally uneventful.
Happy Trails!