Does anyone know what they might do already?  A little Googling suggests that 
http://www.cdcta.com might be a starting point for finding out such efforts.  It was a CD&CTA Memorial Day event where he was paralysed.
I seem to recall there being paralysis charity stuff at equestrian events, so maybe Reeve might not want something that spooks riders.  Would he want a statue when that money could go to paralysis research?