Determine the extent of the damage. Camper cracks often occur near windows or close to the bottom of the frame. Use the flashlight to see how deep the cracks go and if they expose the frame or any internal components. If a crack goes into the interior of the camper, call your camper manufacturer or retailer for further advice and troubleshooting.
Wash your camper gently. Wash the cracks with a rag and soapy water. Do not use use a spray from a do-it-yourself car wash as this could make the cracks worse, cause electrical problems, or expose the frame and other metal parts to rust. Use a Q-Tip or a pen covered in a rag to clean inside the crack as much as possible. If you see electrical wiring in a crack, do not wash it and call your local camper retailer or manufacturer for repair.
Apply Bondo to the cracks. Using a spackling knife, gently push the Bondo into the cracks so it fills them completely. Shape the Bondo carefully so it is flush with the exterior of the camper. Check the camper underneath the cracks to avoid getting Bondo on the ground. After shaping, leave the Bondo to set for a few hours or however long the instructions on the back of the can suggests.
Sand the Bondo and apply paint. Gently sand the Bondo to give it a smooth finish. Apply the paint gently and use a few coats to assure a good finish. Let the paint dry between coats according to the instructions on the can.
