Was going to sign up to suggest this very thing, but RoccondilRinon beat me to it.
My opinion - Recolor Jango (maybe Angel/Vaderios could create some mockups here) so that he has the same colour armour as OT Boba (pre battle damage)
Also remove young Boba. This little kid is just one of the things that ruined my childhood preconceptions of Boba Fett as a badass.
As far as everyone thinks. the armoured bounty hunter is boba, but never referred to by name and never seen without his helmet (to preserve the character's mystery)
This would turn (boba) fett from 30 years old in return of the jedi, to much older (and therefore veteran)
This coupled with the mystery added to the character (you only catch glimpses of him, and never find out his age or see him without his helmet), would make him something of a mythical character. Spanning 2 eras.
Something to start off the ideas train:
Recolour Boba and cut all helmetless scenes - maybe superimpose a helmet for the few helmetless arena shots
Maybe give him some new dialogue (in OT Jason Wingreen type voice)
Cut out child Boba - could potentially still have him on the arena podium, but then he's assumed to be a nobody or a boy servant.
When he takes off at the arena, cut there. He never takes on mace and never dies. We just assume he making an escape after seeing the overwhelming amount of Jedi that have just arrived.
Also, off the Boba topic slightly, I think the Jedi and the republic should already be aware of the Clone Army from the start (thus eliminating the ridiculous Obi Wan detective sifo dyas sub plot). This could be achieved with some clever editing, and using the analysis droids deleted scene (and dubbing new voices or subtitles for the droids that link the dart immediately with Kamino rather than all the deleted archives nonsense)
The entire clone army made in secret thing went nowhere, and the Jedi and the republic were happy to make use of them despite not knowing the agenda of who had them created. Dumbasses!