What do the lines “and I drive the main line”, “Searching in the sun for another overload” and “If it snows that stretch down south will never stand the strain” have to do w/ football?
Answer: NOTHING.
It's actually "and I drive the main road." Our protagonist is an offensive lineman seeking to "drive the main road" by opening holes in the offensive front line for his tailback.
"Searching in the sun for another overload"--our protagonist is on the lookout for the defense overloading the line, say, by moving a safety forward.
"If it snows, that stretch down south will never stand the strain." A "stretch" is a pass-oriented offensive formation, and snowy conditions would hamper the passing game.