Chicken halves, can be cooked, perfect, without the pan. Shoot for a sixty minute cook, so you'll have to figure out your own temperatures, dependent on chicken size. Halves on the top grate, use the water pan, inverted over the chickens, for an extra special touch on the skin.
I leave them skin up, the whole time. When I'm done cooking this way, the halves look like a picture. All plumped, shiny, with no grill marks, on the skin. Brine the chicken halves for about 8 hours prior to the cook, then let the skin, air dry for about 4 more hours in the icebox. Give them a good rub prior to cooking, slightly heavy with the paprika. Spritz with a sprayer, filled with apple juice and balsamic, every ten minutes during the last half of the cook.
Good luck.
Jim