There isn't really a recommended setting.. it depends on several things.
The chassis and panels should have been centered in Max prior to exporting to scx... that way the cfg will be set at 0.000 0.000 0.000 for the all body parts, but the flaps are not exported, they are just script and vary from car to car. I am downloading Tyago's PS13 now, so I'll take a look and see what it's like... (Tyago's stuff is usually good).
Added 36 minutes later:
Ok, I see the problem now, lol...
I have adjusted the hatchback first, so it doesn't go so high that you can't reach up to close it.
Before
After
The trunk models need a bit more work, as they are using the same flap setting as the hatchback... which is not right.
I will look at that tomorrow, as it's 5am here now and I need to sleep. Anyway, you see what I mean, it can be adjusted to whatever suits.
Back tomorrow with update