ocal rentals tend to be unlimited mileage, whereas one-way rentals often have a per-mile rate in lieu of a drop charge

That's usually for corporate contracts, where the rental company is basically not charging for the difference in relative demand, and the corporation will always know exactly how much it will spend on rental cars. For retail customers, which do exist on FlyerTalk, the rate plan is usually unlimited miles, but a higher daily rate for one-ways.

Before booking, call the location(s) you're considering renting from, talk tote manager and ask if they have any cars that need repositioning to LAS. If they have a vehicle they need to get there, you can negotiate a better deal.

Once upon a time, most rental outfits were independent franchises, and that was a common strategy for getting cheaper one-ways. Now that most locations use an interchangeable corporate fleet, that approach is much less successful than it used to be.