Purist idea that I can understand, but you would lose Clone Wars and the good The Clone Wars episodes (as well as the best of Rebels that is based on the previous tv series). The will to erase EpI and EpII (even if they contain good material from time to time) is something I could agree with (could, not would 😃), but I like most of EpIII so I wouldn’t erase it for Rogue One that I consider to be inferior in every way (besides, both Darth Vader scenes only make sense if you do acknowledge EpII-III…). So let’s take R1 as EpIII, but you need some kind of EpII made of ROTS with scenes from EpI-II as flashbacks (since R1 uses flashback structure this is no longer a stylistic issue). Then take 2003-2005 Clone Wars as Episode I (but it’s a cartoon…). Don’t know if the Han Solo movie could do the trick as a prequel episode. So it could go that way:

EpI- ROTS with TPM and AOTC scenes as flashback (3-1 movie edit ?)
EpII- Han Solo movie
EpIII- Rogue One

or
EpI- Clone Wars
EpII- ROTS (theatrical fanedited, 3-1, whatever you want)
EpIII - Rogue One (theatrical or fanedited)

(I don’t like it - I’m very fond of the I-VI structure of the main original hexalogy saga - but the idea is fun)