Rigs and Brews hosts the main biggest gatherings around here, usually 2x a year. They just had their annual toy drive so the next event will probably be closer to summer. You can find them on instagram. Basil's Garage in Vista hold events a few times year and they pretty good about promoting other events on their Instagram. Rigged For Dirt is another group that hosts events. Also, The Average Overlanders podcast is based out of the area and they tend spread the word about meetups etc