Last year when I was plat, I check a ski bag, a boot bag and a suitcase in DEN going DEN -> CLT -> LGA. I told the check in agent that I wanted to check in the boots and skis as one item. The agent made me open up my boot bag and put everything that wasn't my boots (jacket, sweatshirts, etc) into my suitcase (which still ended up being under 50lbs). For reference, I was not using a huge boot bag, I was using a Hudson Sutler weekender, which is smaller than a regular carry on at 12.00" x 12.00" x 22.00".