This simple modification allows me to carry a canoe, ladder, long lumber or anything else that is too long to fit on the trailer.
The front portion is all knock down and slips onto the trailer and requires nothing to hold it in place. The back portion is bolted to the end of the tailgate and is cut at an angle so that top is in the same plane as the top of the front section.
The lumber was left over pressure treated since it spends lots of time outdoor in the weather.
IA critical point to consider is the portion of the overhead payload that will overhang the tow vehicle. If the you need to two in areas with hills the overhead payload will come close the tow vehicle any time the trailer and tow vehicle are not in the same plane. This happens when the tow vehicle is on a flat section while the trailer is still on the hill.
It would be a good idea to put some stops on the ends to ensure the overhead payload doesn't slide. This has not been a problem, but it would give piece of mind.
This is modification is simple and very valuable if you need to carry long items