You did a very nice weld job there. It looks very good. I have a feeling your hitch and frame is much stronger than the trailer frame it's attached to. No doubt the frame you built will be able to haul, pull, or carry just about anything. But, not so sure what the trailer is capable of handling though.
Now that you have it installed, take it out for a dry run. Have someone drive behind you, see how much shake or wobble the 2nd trailer has. Might even be a good idea if they could record it so you can see what's happening yourself.
Start by driving slow and increase speed a little at a time so you can learn it's limitation. It might be flawless and, who knows??? you may be able to run 80 mph. On the other hand,... well ... just start slow, build your confidence your plan works and works well. Also, have a 2 way communication with your chase car. If something happens that's funky, you need to know immediately so you can slow down.
There again, I think your self-built hitch is fabulous. Not so sure about the integrity of the camper though. Road test it thoroughly before towing for real!
