I currently use a vornado space heater and aim it at a couple of carboys at once. I think it would work just as well for a plastic or metal fermentation bucket, but I have just not had the need until secondary. For temperature check, I use an infrared thermometer and move the space heater closer or further away, depending on my desired target temperature. Typically the low heat setting a few feet away gets me in the 75-78F range. I thought about getting brewbelts but wasn’t sure if they were worthwhile. If you go the heating pad route, read the reviews first. Lots of comments that they are ineffective, but may depend on the source.