Hi Chuck,
The vent comes off the top of the tank, up through the floor, under the counter and hooks into my roof vent for the rest of the system.
The straps were made from galvanized strapping which I wrapped in Armaflex pipe insulation (from Home Depot) to prevent any rubbing. The tank is a very tight fit, so the straps and the the pipe connections to the plumbing have that baby in there very tight. The straps are bolted to the frame, and I also riveted them as well for a backup. I don't think it can go anywhere, but will keep an eye on it during our shakedown cruises!
You can get info on the composting toilet at:
Nature's Head - Eco-Friendly Waterless Composting Toilets for Marine and RV use.
Thanks!