Heroic Rancor Solo Without Jyn/CLS?

Depends on how much effort you want to put into it. Putting together R2 and Teebo can effectively give Teebo perma-stealth but is a boring slog to play that way. Zader/Tarkin/Magma/TFP can get you close, but isn't very reliable.

If it helps, I do have toons like Thrawn, shore, Nihilus, etc, 7*'d and geared.

They don't mean much for the rancor. You need a toon to apply tenacity down and the rest to remove TM. You will not out DPS the rancor and fracture doesn't do a whole lot. I was using Zader/Tarkin/Magma/TFP/Rex until CLS came out, it would usually get me to P4 and sometimes a solo.

Probably Teebo, QG, Rex, Thrawn, TFP can do it. Not sure about auto.

The key things are turn meter removal, damage and tenacity down.

Zeta Vader (tmr leadership) tfp or Krennic(tenacity down on basic) and any other three empire or Sith allies will do a decent shot. If you can include magmatrooper (tmr on special) and thrawn (fracture has speed down on raid bosses which helps).

You have raid Han and he can do tmr as well so you can probably do a good team with him but you would need to really gear him up.

I was able to solo with Zader, Thrawn, Han (zeta), tfp, and Tarkin. It's still rng dependent so auto might not fly, but it'll do the job.

OG rancor solo team before all the legendaries: Teebo (l), QGJ, Rex, Dengar, Ewok Elder.

If you have thrawn feel free to replace elder with thrawn.

If you have Zolo, you can replace Rex or QGJ with Zolo.

If you have Ewok Scout, you can replace Elder with Scout.