Want to fly into salt lake and drive down to Zion. Any suggestions how to do this? Open to renting an rv one way.

Probably easier/cheaper to fly to Las Vegas and rent a car and stay in a motel in/near Hurricane.
Depending on how much time you have, you may want to see one or more of the other Utah National Parks (5 total).
With more time, you could also see the North Rim of the Grand Canyon.
Things to see in the Las Vegas area include, Valley of Fire State Park, Lake Meade and Hoover Dam.

If you are going to Zion, also make the trip to Bryce Canyon, which is nearby. Stunning place.

Hurricane UT is about 30mi from Zion park. I think you are much better off staying in the town of Springdale, which is immediately outside the park. Plenty of hotels there.

Is there a reason you want to fly into SLC? I'd fly into Vegas myself.

And do you want to RV particularly? Renting a car and staying in hotels/motels would be cheaper/easier driving.

When is your trip?

An RV rental out of Las Vegas might be less expensive, but I'm only guessing. However, you must have advance reservations for camping in the Natl Parks.

There are a certain number of first-come-first-served camp sites, but you must be at the campground circling like a vulture by 8am in order to snag one, and you will be lucky if you do.