While I think you have a lot of good options, it's actually, too many & I'm not a fan of requiring all the new characters.
I've narrowed it down & tossed in a couple along w/ the Cap Ships they go with.
No new characters needed as well.
Chimera:
TIE Advanced v1 - 7th Sister
Executrix:
TIE Outland - Moff Gideon
TIE Heavy - Crewless
Sentinel-class Shuttle (or another Lambda / or TIE Boarding Craft) - Krennic + Stormtrooper
Executor:
Nothing for now: They just got Punishing One & that thing is forking up Fleet Arena horribly right now.
Negotiator:
Jedi Delta Starfighter - GM Yoda
ETA2 - Aayla Secura
Endurance:
ARC170 - ARC Trooper
Nu Class Shuttle - Cody
V-19 Torrent - Crewless
Finalizer:
FO: Assault Lander - FOX
Profundity:
Rebel A-Wing - Crewless
Home-1:
B-Wing - Crewless (Tank)
Luke’s X-wing - Farmboy
Malevolence:
Droid Tri-Fighter - Crewless
Raddus:
Resistance A-Wing - Crewless
Leviathan:
Nothing for now: Better they fix Punishing One first before screwing up the meta fleet any worse.
Some fleets would still only be at 6 but I'm fine with having a little room to grow.
The stuff I mention above is all things that I think are CRITICAL & EASY both based on the existing graphics & shortage of the fleets.