What exactly are you looking for? What would the mission be?
Check out the Escapees organization and the DOVEs group (Disaster Operations Volunteer Escapees). Note the last thing a disaster needs is a bunch of untrained people showing up to utilize already stretched resources. You’d be better off working with established disaster relief organizations. The Cajun Navy is a short-term search and rescue group, not a disaster response team.
No. Government-based emergency management isn’t always great (e.g., look at Maui) but the last thing any large-scale disaster needs is a flock or RVers self-dispatching into the affected zone trying to “help.” Source: I am in emergency management/EMS. Leave this to the organizations that are actually positioned to do a coordinated, proper job helping.