Just hold on, there is an easy solution.
Mod your shifter on the end to take the Harley style rubber shifter, it's about 1 inch diameter and ribbed.
Then mount your shifter at about 30 or 40 degrees and use the back of your boot to shift up and the heel to shift down.
IT may be a pita for around town, steady use, but to go for aride once in a while it should work.
Very therapeutic and will put a big smile on your face.
I know this because I was in a cast for a year, but I was still able to dragrace and win..
The rules were a bit lax at our track in them days.
So hang in there, hope it works out..