What requirement must trucks with a cap or slide-in camper adhere to regarding tailpipes?

Trucks equipped with a cap or slide-in camper must have the tailpipe configuration that ensures exhaust gases are adequately directed away from the vehicle to prevent any potential health hazards for the occupants. In this case, the requirement for the tailpipe to extend beyond the rear and side of the body is critical. This positioning helps to ensure that exhaust fumes do not accumulate near windows or entry areas where passengers might be seated or entering and exiting the vehicle, significantly reducing the risk of carbon monoxide poisoning.

Tailpipes that extend beyond the vehicle's body are also designed to promote better air circulation and exhaust dispersion, enhancing the safety of both the occupants and other road users. In the context of this question, this option aligns with regulations intended to ensure vehicle safety and emissions control.

Other incorrect options do not meet safety or regulatory criteria required for the setup of a truck with a camper, highlighting the importance of proper exhaust routing for safe operation.