I don't know if this works for rsd, but it might.
At my rehab therapy place, one of my good friends had a severe stroke. When they work on getting him up and walking, they use a brace for his leg. What they did was cut out a styrofoam board to go all the way up the leg and it covers half of the leg (back end) and then duct taped it on to sturdy it. Then they duct tape it to his leg to make a sturdier for him to walk. You can always line the inside of the brace with cotton or something soft. You can use this with a walker or cane or even without anything if you feel sturdy enough.
If that doesn't work, I believe the make ortho boots that cover your whole leg so you can always talk to your doc about getting 2 of them.
Best of luck Vanessa