I assume you will be arriving internationally at TBIT, so you will already be outside of security upon arrival, same as normal and same as at SFO. There are terminal connector shuttle buses that run on a regular basis. Realistically, almost all of the official shuttle buses will stop at both TBIT and T7, so you could just hop in the next one to pass (they are running continuously). Just be sure to ask the driver if they are stopping at T7 when you board, unless it is the Terminal Connector shuttle. You could also simply walk 15 minutes from TBIT to T7. Regardless, you will still have plenty of time to enjoy the Polaris lounge before your 16:48 flight from T7/T8. Even if the tunnels were still open, it is still faster to walk airside and reclear security at T7, rather than reclearing security at TBIT and taking the tunnels. T7 also has a Gold Track security line.

FWIW, there is a taxi queue directly outside of TBIT, but it makes absolutely zero sense to go that route when there are countless free shuttles available and it is an easy walk away. You would also likely make the taxi driver quite upset, and justifiably so.