It is harder to steer a truck with a welded front, it will not turn as sharp, but as tim said, you shouldn't need to steer much in the pit, just small adjustments.
Different gear ratios can accomplish the same as larger tires in the front. I just used different sized tires, because I wanted TSL's in the front and boggers in the rear. Stick with narrower tires in the front as long as there is a bottom to the pit you run in, You are trying to cut through less mud that way. Also, trucks running wide tires in the front seemed like they could never keep it straight.