It would be great if someone could give me some advice about cycling with a severe injury.
In 2010, I got hit by a car while cycling. The car snapped my leg in half. Owing to sequelae from an intramedullary rod implantation to "fix" my tibia, many nerves in my left leg are destroyed, and there are lots of extensive scars and weak spots on this leg. I later had the rod removed after the skeletal pain it caused became unbearable, but this did nothing for the neuropathy.
I have a lot of neuropathic pain and numbness in my knee, and I cannot feel most of my foot (where the screws that held the rod used to be and the surrounding area). I am thinking that I need to spring for clipless pedals; I've never used them before, but as I've been cycling on my platform-pedaled beach cruiser for a while now, it's quite clear that my foot doesn't have enough sensation to stay on the pedal for very long.
I also have extensive muscle atrophy in this leg. I've done lots of physical therapy, but the leg is still like a shriveled-up toothpick. I naturally have a stick-thin frame, but I want legs like tree trunks and to be able to cycle a hundred miles with this leg, even if it kills me.

Any advice would be much appreciated.