Yes, the fairgrounds are by the airport
. Your choices for RV parks in Monterey are slim. We stayed at Marina Dunes a couple of years ago. The park was reasonably well maintained, the management was pleasant, but it is next to the Freeway. We were on the side away from the road, and we weren't bothered by road noise. Marina Dunes was within walking distance of a beach, but you have to hike across the dunes to get there. It is not convenient to anything else, though, so you would need a toad or a rental car to visit any of the local attractions. It is located in Marina, next to Monterey.
The Cypress Red Roof Inn in Monterey advertises itself as having an RV Park. It has hookups along the back row of the parking lot, and is definitely sketchy
If you don't need to be in Monterey proper, you might check out some of the surrounding areas.