Yea most soap makers aren't rendering their own tallow. My wife does the water method to make her soap and I'm talking her into making a post on here to share with you her process..

Here is the tallow with water and salt for the last (3rd) rendering. You can definitely do a crockpot as well but she likes the bigger stockpot on the outdoor stove (she is banned from using our kitchen stove since 2 batches erupted lol)