It's really hard to tell on that trailer where the proper location would be? A Super Cub is only 240 pounds. You definitely want some weight on the tongue, & I have to believe the rear trailer ramp has some weight to it. Then again the location of the trailer axle may take that into account. If he were hauling something that weighed close to the trailer's capacity, the location of the load would be more critical.
This sort of tells me he did good with the load - "I was worried about bottoming out the rear springs, but to the best of my knowledge, that never happened. However, the back bounced around more than usual with the empty trailer attached. Having the trailer loaded did away with that sensation."
It's better his tongue is pushing down on the car some verses having it almost balanced & lifting the rear of the car at times. Heck, I am more of a load than that Super Cub!