Hey Chris and G
Enjoy you on YouTube
The hitch set-up shown should surely work...within reason.
The straight line pull (towing capacity) of the set-up would be the rating of the weakest link (hitch doubler?).
BUT, the rating I would be careful with is the "tongue weight" or the torque placed on the parts.
The math here is that torque is multiplied by lever length. And this set-up appears to much more than double the length of the lever action on the hitch...like:
So, if the hitch is rated for 500lb tongue weight, this set-up reduces that rating by a factor of the length of the set-up...probably below 200lb (that's the weight of the tire carrier and tire, the cargo rack, the waste tank and its contents)...so be careful.
Just FYI, slightly exceeding the hitch tongue weight will not cause immediate catastrophic failure of the hitch. BUT it will fatigue the metal and overtime cracks can appear leading to failure.
A receiver added on the car is a good idea..and be sure to check that receiver's tongue weight rating too.