Need help/pointers to achieve Californian Drifter Achievement

I hope someone is willing to help me out a bit. I want to get the Californian drifter achievement someday. I know it’s really hard, possibly the hardest one for me to achieve.
I did some drifting in F3 & F4 (AWD HKS). I can handle drifting in FH2, I am not great, but good enough to tackle the harder achievements like Coop drift achievement on storm island (12 out of 16).

I have tackled the other drift achievements in F5 with a RX7 with a well known tune. Due to new to drifting with a RWD car, epecially A700 it took me a while to get some feeling for the RX7 on Indy oval. I can now get perfect drifts relatively easy. I understand some of the drift basics with this car. Mostly due to indy oval being a wide track so i can save drifts more easily. I did some monthly rivals on the bugatti circuit, i am able to get 15-20k in a lap clean (not constant though). Bugatti track is also wide enough.

Now onto Long Beach, my main issues:

  • The with of the track. Most corners are to tight for me to throw the car arround. Escpecially corner 1, 2-bus stop like chicane, 5, 6.
  • Keeping speed up, due to rewinding a lot I loose a lot of speed I cant get up quick enough to catch the next corner. Especially corner 2, i drop to below 20.

I did a few runs with rewinding, got to roughly 12k points. Did a few runs with hardly any rewind and got about 10K. I have the details/layout with the corners and the points that need to be get to get a total of 15k+. I loose the most in the first section, roughly 2k short.

The RX7 is possibly not the best car to start learning RWD drifting with, i know that. But my philosophy, if i want to learn it, then learn it proper (also if that takes much more time).
I dont have a steering wheel, just a normal controller (set to normal steering), all ai off, manual shifting.

I try to keep the rx7 arround 70 - 120 km/h, so i use 2nd or 3rd gear depending on the corner. 2nd gear is a bit tricky due to the immense power output at the last 2000rpm.

What should be an comfortable speed for my “abbilities” with this car/tune arround long beach? I need some info so I have an idea to work with. I have watched quite a few replays from people on the leaderboards, I can see how the corners are attacked, but sadly i cant see the speed/telematry they are using on those corners.