I don’t see too much of a problem with the existing chicane at the end of the main straight (having been seated in the grandstand there for the last two years). The problems lie elsewhere
and what happens at the chicane is just a symptom.
OP has the right idea as a starting point…
1. The ‘jink’ just before the northern hairpin is bad. It just slows the cars to a halt and bunches them up. Then the leading car gets on the throttle first and away from the pack all the way down the main straight so by the time they get to the chicane the following cars just haven’t been able to get close enough for an overtaking move.
Solution: get rid of the ‘jink’ before the northern hairpin and make the hairpin rounder and wider on the exit, instead of the slow pointy V it is today.
2. The chicane at the end of the main straight is a tight Z (upside Z) shape. So even if a car gets inside to overtake at the first part, it is hard for them to make it stick as a car running wide can just take the inside line at the second part and get back in front.
Solution: keep the first part tight but make the second part more rounded with a more open exit onto the back straight ie a 2 (back-to-front) shape.
3. The rest of the circuit is fine as it is
So how would this benefit ? Well if you put these changes in place then
a) it would create a new straight leading into the northern hairpin creating a new overtaking opportunity
b) it would allow cars to get a more equal and faster exit onto the main straight, giving following cars a better chance down the main straight
c) it would allow cars that get on the inside at the chicane to have a better chance of making it stick on the exit of the chicane and those that did not would be right on the back of the car in front exiting the chicane
d) the more equal and faster exit from the 2nd part of the chicane would give following cars a better opportunity for overtaking down the back straight and into the 90degree corner in front of the south grandstand.
e) and with having to defend at both the northern hairpin and at the chicane, any and defensive compromises and mistakes made by the car in front would improve the chances of the car behind being able to make a move. Get your defence wrong at one of the corners and the car behind will get you down the next straight and into the next corner.