I just acquired an ICE QNT (2006) with all 20 inch wheels. I am methodically replacing and upgrading. The bike runs nicely. Here are some of my plans on upgrading:

A - Adding a mid drive -Bafang BBSO2, 750W mid-drive electric bike motor
- ref: Electric Bike Mid drive Systems - eiProject

B - Add a pannier rack
C - Change over to tubeless tires for better efficiency
D - Add turn signal lights
E - Removing parts and bead blasting then powered coating

Custom Modifications:

A - Modify my seat for better comfort to try to achieve lumbar support.
B - Modify the seat to allow it to slide forward/backward. This would allow me to change position without having to change the length of the crank extension pole. I would like to be just a few inches back toward the rear than I am now.
C - May fabricate a wheel extension so that I can mount a 26 wheel as an option.
D - Create a trike assembly table so that I can assemble/clamp parts or weld. This would also allow me the rotate the trike so that I can easily access the sides or underneath.