Not 100% sure that is a good idea. You'll need a heater in the 300 liter container and that will require a lot of power. I'm only heating a 2 gallon/7 liter bucket. You want a container that will last multiple days so you aren't refilling it every day, but not so much that it will cost you an...
I'll second what @RoyalChick said. You can indeed keep a pipe setup functioning in winter using heating tape. I found it easier to use a heated bucket with nipples and then switch to a PVC pipe setup when it warms up. I'm tempted to simply abandon the PVC pipe setup, but it does have more...