Is it legal to throw a rave on a private ranch outside the city limits without a permit?

You need a lawyer. I help run such events. There are many factors involved. Even if this is outside a city, it is still in something else, such as a county. Most counties require permits for events. There may be zoning that prohibits such a use, or such a temporary use may be allowed with a permit. That is why you need a lawyer who knows about these things. I strongly suggest you do not call it a rave, and call it something else that sounds friendlier. The word "rave" has the implications of drug use. You almost surely need an event permit, insurance, plans for parking that will be part of the permit, proper zoning for such an event. It can be quite difficult to get the needed insurance, and insurance is usually required for the permits. You will also need to follow sound ordinances or might even need a sound permit. Every element will have to be inspected, such as every stage or platform, every scaffold, electricity, food service. This is not impossible, and there are groups running such events all the time. However, the permits take time and money. You will need to work with good planners who know how to do a layout and how to do a good set-up and take down. You should see first if you can secure the permits and insurance before selling tickets. When you sell tickets, you should sell advance, no refunds. You absolutely cannot permit the sale or use of any illegal drugs, or the land owner risks losing the property.

You are not without a government. It is either a township or county. You have to follow their rules.

No one can give an opinion to guarantee you possible liability, but it sounds goods per your description.

You will probably need to notify officials in the county the ranch is located in. While it sounds like you have carefully planned this project, there are various agencies that may need to approve the project - everyone from the Roads Department to Water Quality to Fire and Sheriff's Departments.