Footrests for stoker
I solved a similar issue on my tandem. Measure the frame tubes. If you are lucky you may find one of them is the same size as a handlebar stem. In my case I bolted a 1 1/8&quot; x 1 1/8&quot; stem in an appropriate area for a foot rest. I then cut a straight (no sweep) 1 1/8&quot;  handlebar to about 14&quot; long and installed it in the stem, I then added handlebar grips so my stoker's feet won't slip off and to make mounting the bike easier. The stoker can pedal as long as they can, then take a rest without cranking.