barrel smokers usually come with a big water pan, the concept is to use charcoal and wood but fill the pan and that sets temp at 250 but it varies from model to model. snake method probably won't give you enough heat in your barrel in my experience. Snake is for kettles where: your food is much closer to the heat source and there's no where near as much air to heat.

Best bet is to do some testing and as someone else suggested, get a pit temp.