To be fair, they usually have one character with a costume.
And Trunks just need a closed jacket and a scarf. Literally. That's the only change. So yeah, it's doable.
As for Trunks's gameplay, I think he'll have a slash super + heat dome as lv 1 supers.
And burning attack lv3. You can turn it into a lv5 super and have the final slash kill.
He'd have another super, the Ikari install, that would change his slash super to have the spirit sword effect with more range.
If you do the lv 5 it has spirit sword effect.
That'd be the best of both world, if you don't want to see ikari, just don't use it, like golden frieza.
The bigger disappointed to me is that there probably won't be a Spirit Bomb in the game.
Hopefully the sequel makes ssj installs for the base forms of characters like Goku. Maybe have different variations to pick from that change what transformation and Supers each character has.
I hate Genkidama in a fighting game because it's not Goku's power. And it takes forever.