The hatch props are now installed and work pretty well. I might tweak them a bit later. The design features I desired were:
1. Plenty strong to support the large hatch.
2. Raising/lowering would need to be a one-person job.
3. Pinned at each end to avoid wind lifting.
4. Raised hatch height would allow suficient head clearance.
Many of the designs used for teardrop builds were unsuitable due to the monstrous size of my hatch and the solo positioning requirement. I decided on using a gravity-drop method, securing the props to the hatch, so they would fall into near position when the hatch was raised.
They are plenty strong. The only hassle is when stepping underneath the hatch to seat the props in the base "cups". As I walk further underneath the hatch, the "ceiling" becomes higher due to the hatch curvature. I'm at about the max. of my reach when manipulating the props into position. That will be the tweaking part, moving the base cups closer to the countertop edge so they are within closer reach while I'm still holding the (lower) bottom hatch edge.
I used kick-down door stops and after removing the rubber foot the 1/2" EMT conduit fit perfectly inside the rubber foot cup. That was a nice surpise, I had expected to cut/grind the stops in order to insert the conduit. I drilled and bolted the conduit to them (no pic):

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Base cups were fashioned using 3/4" grey electrical conduit (perfect fit for the 1/2" EMT conduit, large enough and not any slop) and secured with machine screws/nuts/straps to the endwalls. A cap was used on the end. The curbside "cup" is 4" deep and the streetside "cup" is 3" deep. When raising the hatch I insert the curbside prop first, then with it captured I insert the streetside prop:

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The door stop was screwed to the hatch rib. (Don't know WHO cut that crooked rib,,, yikes! Might add a hatch liner after all.)
Foam pipe insulation was added to the conduit:
When lowering the hatch, I raise it up and the props come out of the cups. Then, I swing one toward the countertop, then the other. As the hatch closes, they slide across the countertop. I might add a couple of spring clips to the underside of the hatch so I can clip them in place, haven't decided. The folded, travel position was checked for clearance. Ok.
