2025 Non-JBL: Verify my plan?

Picking up a 25 limited next week, non-JBL. I have a 5-channel amp I want to install, with 2x JL 8" subs. Not sure yet if i'm going to upgrade the speakers. For now, i plan on running the stocks (we'll see how long that lasts) with the bet being cleaner power from an amp will make them tolerable. It's a lease, so if i can spend money elsewhere i'd prefer to.

If I understand it correctly, I have a couple of ways to do this:

1. I need a TTunes integration harness to get signal to a LC5i to feed RCAs to the 5-ch amp, and the other half of the integration harness to go from 5-ch amp back to factory HU for the speakers. Sub gets signal from the 4-channels coming from HU, correct?

Or,

2. I could use a Beat Sonic ENX-T317 pre-amp/DSP from factory HU to feed RCA's to 5-ch, and use half of the TTunes integration harness to go from 5-ch amp back to factory HU for the speakers.

Or,

3. I could skip amplifying the stock speakers, use a Beat Sonic ENA-3T3 to feed RCA to 5-ch amp and bridge for subs.

3b. I also have a LC2i in my possession, so if i could pull signal from perhaps the rear channels to drive the LC2i, I could also use that to run the sub for option 3. Just not sure where to pull signal from cleanly.

Thoughts? Do I have anything here incorrect, or are there any other/better ways to do this? I know TTunes has a DSP, but I also know its not preferred, so I didnt list as an option.