You can already do #1. I've been using one of these [1] plus an Apple 30-pin dock to lightning converter for years. It's been worth it just because there's only one thing to plug into the phone, and it allows you to route your cables nicely if you want.
Yes, I do this too, and it angers me because it proves that this datapath is possible to build. Double-dongle sucks, but it works. I marvel at how backwards apple can be when it wants to be. I wonder if this new headphone dongle they announced can be hacked to do charging.
My car doesn't have aux, so I've been achieving it with a Bluetooth FM transmitter. It's not ideal with occasional FM interference when traveling, but it's also ≤ $50 vs replacing the head unit, etc. And it works in every car.
[1] https://www.amazon.com/SunbowStar-Universal-Charger-Adapter-...