I think you're ALL crazy!
I hate extension hitches no matter how stout they are. The laws of physics cannot be broken; putting your hitch that far behind the axle gives your trailer a lot more leverage against your truck.
I tow a heavy (sometimes its 10,000 pounds) trailer with a dually carrying an 11.5 camper.
Rather than run one of those insane long hitches, I stretched my trailer tongue to reach the hitch right at the truck, under the camper. My truck is a 4WD (so it sits a little high) and I have the camper raised a few inches off the bed floor, and that buys me enough clearance. I've driven thousands of miles with no trouble.Yes, you have to watch your approach angles, but it's worth it.
There is absolutely NO way a truck with a fairly heavy trailer can drive as well or be as safe with the hitch three or four feet further behind the axle, regardless of how solid the hitch itself is.
Anyone who is capable of fabricating a hitch extension, or is going to pay someone to do it, should consider doing it the other way. Bring the trailer up to the hitch!