nice rack! ANyway- I found this on another seller site. Maybe it answers the "mods necessary for installation question- You are BOTH right.:
If the bike does not have the factory backrest, you will be required to drill 4 holes in the existing cover plates on the rear plastic bodywork. Or, you can use the Honda rack mounting system that comes with predrilled cover plates. The Honda part numbers are 08L73-MJG-670ZA for red cover plates or 08L73-MJG-670ZB for black cover plates.