On more days than not, I jump in the car with my camera and 150-600mm lens and take a similar tour around my town. I stop at a salt panne, drive a mile to a path I walk through a marsh, then over to a seaside cliff and walk a beach. Back in the car, to a local park fed by a brackish creek, then over to a yacht club for a nesting eagle.
That's 10 short trips in and out of the car.

Where can I safely and quickly put my camera with the lens attached that will keep it reasonably save while a travel from stop to stop?

I use styrofoam form from packing box, that keeps it from rolling, but doesn't really provide enough support over the length of the lens. I thought about a box of dried beans, but that would be full of dust. Perhaps a box of washed pebbles would provide a base.

Yes, it it's not a quick stop, I keep a oversized backpack/camera back in the trunk, but's unlikely to get in there for a 2 minute dirve.

Anyone have have a gadget that will hold the camera and lens in the car?