Assuming you are burning wood and not charcoal, two options come to mind. One it to keep a fire going in a kettle or burn barrel, and move coals to the cooker when you need more heat. The other, and this makes a lot more sense, keep some smaller splits handy, that you can add without as much flare up. That might help.
As for the chicken, my favorite grilled chicken is really just some oregano, thyme, kosher salt and black pepper, all added to a marinade of sliced lemons and olive oil. Let the chickens marinade for a couple of hours, then grill until done. Real simple.
I'm feeling bearish, and I'm packing a Wusthof Grand Brisket slicer from MABA
"perhaps...but then again...maybe not..."