40" my wife is under 5' I am 6'
The top of the table can be no higher then 40" from the ground.
The distance from the ground to the bottom of the bumper is 16"
The table in my case is 18 1/2" high
So I have a lot of figuring to do.
I probably will simply make the top part first. Mesure it and then cut the support pole to the correct height. I do not want the height of the pole to be to high, this is where the thickness of the arm would be important. I do not want it to twist and brake when opening. A square peace of wood might work better then say a 2x4 And of course a Metal square arm might be The stronger idea.
I am thinking about not just the table weight, stress put on the swing arm, but what I might put on the table. Like my Tankless hot water heater.
Most SUV spare tire units have a support coming from a higher point as well as the bumper for added support. I could do this with my tailer I have a 2x4 frame built into the rear of my trailer.
I am planing fo add a Chain or cable to the tire and connect the other end to the frame for safty. The swing arm will be bolted to the bumper when closed.
I will try and do some drawings of what I said above and photograph them.