You could use a drip pan, but not necessary at all. Unless I was trying to do a low/slow on the gasser, I've never used a drip pan on my gasser.
If you have north/south burners, turn on the left side and put the chicken on the right side. Since the right side burners are off, you should have no problems with drips hitting the flav bars below. To clean the flav bars, 5 seconds with a putty knife or wire brush is all you need.
Also, I'd recommend a vertical poultry rack (basically beer can chicken but with the center open) for this cook. The results are rotisserie-esque..