Thinking about adding a roto to my 27" Weber kettle. For those of you who use a roto with a charcoal grill, do you put the fire directly underneath and let the fat drip and vaporize on the fire? Do you put the fire(s) at the edges and place a drip pan under the meat? Do you cover or leave open? How long will a 3-4 lb chicken take on the roto, when it takes about 1.5 hrs on an indirect smoker at about 300 dome temp? Thanks.