Don you don't know you can't do it till you try. Its not that you couldn't build a shifter but its kind of like reinventing the wheel
I remember back when I was in H.S. had a 50 olds with lasale trans couldn't afford floor shifter yet but HAD TO DRIVE. I got two steel rods beat them flat on one end drilled holes and filed till I could use them for shifters. one was 1 &R the other was 2&3 No speed shifting but I was on the road.