Hitch Extension Questions for Pulling a 7 x 14 Cargo Trailer

Thanks for the info everyone! The truck that I have is a 2018 F-350 Super duty 8' dually diesel. It has a 3" hitch receiver with reducers on it. The truck camper is Cirrus 920 NuCamp, it weighs in around 3,200#. I took it to a shop where they put hitches on and they said that I would need a 34" extension which just puts it just a couple of inches past the truck camper bumper.

I want to make sure this is SAFE for everyone.

thanks.