Here are somethings to consider
I recommend that you start with your state fire academy. Ask for the qualifications to be an incident commander, fire officer, chief officer. My state uses the NPQ system. Our state academy has a list of classes you must complete to obtain each certification. Then there are annual requirements to maintain each certifications
I work in a combination department myself. We have a chief of the volunteers. He is more than qualified to function as a command officer.
He has more training and certifications than many of our career officers. Most anytime he shows up at one my fire scenes I ask him to take sector command somewhere. However policy is any volunteer is subordinate to lowest ranking career firefighter on scene.
I have found that most volunteers want to do a good job. They just need to be guided in the right direction no different than career firefighters. I would recommend that you call this volunteer chief. Ask for a meeting. Have your facts together. Express your concerns as a group, (Safety, Accountablity, Free Lancing, Training) whatever your concerns are. Don't attack him, stay on point and document your meeting. Your goal should be to have a positive meeting with positive outcomes.