Turn the door hotdog, then rest it on the NDS pedal. If you put the center of mass towards the rear of the bike, the door will try to rotate but get caught on the bottomside of the handlebars. You can then put your hands on the bars, and walk your bike very easily, no supporting the door necessary. Just watch out that your skewers don’t rough up the door.
When you started describing this I was waiting for the part where you’d hop on and pedal off on the DS crank, door bobbing up and down. then I was gonna freak out.
Last year on my porteur rack, I carried a 70lb box of steel shelving, the kind in restaurant kitchens. The trip was 13 miles and a couple hours. It was fun, but I didn’t get as many looks and cheers from middle aged people as I did the time I rode an empty keg 2 miles home. /me me me.
One time my kid got too tired riding his bike so I put him on my shoulders and carried his bike too. We must have looked like a circus act riding down the street.