Locate the exhaust port on the motor home's generator and measure it. Get a section of radiator hose or other flexible tubing that is approximately the same width. It can be slightly larger than the exhaust vent but cannot be smaller. Most vents are about 1 and 1/2 inches wide. Your flexible hose doesn't need to be longer than 18 inches.
Get a long section of piping that will fit on the flexible hose. Its width can be slightly smaller than the flexible hose but not larger. The pipe's length should exceed the motor home's height, so 10 to 12 feet should suffice. Stainless steel or PVC pipe will work.
Attach the flexible hose to the generator's exhaust vent using a wire hose clamp. Make sure the seal is completely airtight so exhaust doesn't seep out at this juncture. Connect the pipe to the other end of the hose with another hose clamp, ensuring you have another airtight seal.
Determine how the pipe will be positioned. It will definitely point upward so the exhaust will travel above the motor home and keep it from seeping inside. Tilting the pipe at a slight angle towards the rear may help even more.
Mount the pipe securely to the motor home's side if you don't want to worry about it falling over. This requires only a pipe bracket or two, and you can use a strong adhesive if you don't want to drill through the RV's body.
