I have 2 ft. platic pipe like you are thinking about and am up in the Catskills. We went through last winter with almost 3 feet thick ice with no issues. I don't have seep collar as my pipe is basically just a spill way that we have a dirt bridge over. Glad I have the 2 ft. pipe as we have seen run-off this year after the tropical storms that nearly filled the pipe.
Our pond is about 1 1/2 acres. You can see photos of it off my home page. Catskill pond designed and built my pond and I think they did a great job.
