Fresh water tank drain.

Getting rid of anti freeze in the fresh tank can be a major pain in the anatomy.

Two places. UNDER the tank or in the side of the tank.. Mine was in the side behid an access panel (same one I opened when filling)

Now because it was NOT in the bottom it was a ton of fun getting the last couple of gallons out.. I ended up slipping a small vinyl tube about 5 feet long into the tank and siphoning the water out. It's easier than you might think.

While there's no real harm to having antifreeze in any of the tanks, if you drain them normally, there should be no need of keeping any antifreeze in them. Whatever miniscule amount of water remains on the bottom of the tank has plenty of room to expand as it freezes, and no fittings to fill and burst/split apart.

If you have any significant amount of water remaining in, say, the dump line between the tank and the dump valve, that could very well lead to trouble; but a quarter inch or whatever in the bottom of a tank is not a concern.

While you are underneath your MH searching for the drain, take a general look around. Bound to find something that needs attention. Don’t forget eye protection

In my unit the drain is behind the driver's seat on the stub wall.

The question of what to leave in your tanks depends on how you winterize.

If you airblow the system till all water is out, don't leave anything in the FW tank. Nothing wrong with leaving a cup or two of antifreeze in the black tank, as it is hard to get water out of the bottom of that tank.

If you winterize via leaving pink stuff in the lines, then yes, leave a little pinky in the FW tank as well.

Don't know where the drain is on your rig but it should be right under the tank. Calls for someone to crawl under the rig and look up.
I vote for an empty FW tank. The pink stuff may be hard do totally get rid of next Spring.

For your FW drain you may want to try posting the question on a Fleetwood forum. But it should be directly below your FW tank, and either a ball valve or cap on the end of the PVC. Probably have to get on your hands and knees to find it. Not sure if the low point drain will drain your FW, but it's worth a shot if you can't find the FW drain. As far as winterizing, for your black, grey and FW, if they are empty they won't burst from freezing. Bursting happens when the expansion from frozen water exceeds the area in which the water is trapped. An empty tank does not need antifreeze. Not sure why anyone would advise filling your tanks and adding antifreeze. Seems like a lot of wasted water and antifreeze for nothing. And you didn't ask but, you want to drain your water heater as well and use a bypass so you aren't filling that up with antifreeze. To drain your lines, use your low point drain and it's usually a good idea to blow the lines out with compressed air. Take special note to if there is any water in the line near the pump. Those small clear caps on the water pump screen are notorious for cracking when freezing occurs.