Didn't mean to scare you off. All types of Rvs go through the tunnel daily. The switchbacks are not that big a deal, the curves in the tunnel are slight. Drive it in your truck and I'm pretty sure you'll leave via the tunnel.
Truthfully, the most disturbing part of the tunnel drive for me is the first couple of seconds adjusting to the change in light. Have your headlights on and wear sunglasses. Take them off as you enter the tunnel. This helps me adjust to the dark tunnel. On my first time through I followed a big tour bus. I just did what he did and it was a smooth introduction to the Zion tunnel. Give it a try
Marvin