Tone: From left "Bass" 5,0,5,2.5,2 to right "Treble"
Balance: Rearwards until the circle intersects with the center circle, so a diameter down.
In order to compensate for the lack of speakers we need to look at what they are and what they do. We have:
For the front grill, the 2 side 4" speakers and the middle 1" tweeter. The premium has the middle 4" speaker working as well.
The side mirror 1" tweeters and A pillar immersive sound 2.5" speakers are all exclusive to the premium.
The front doors have an 8" woofer, the rear doors have a 4" speaker. Available on all trims.
The rear parcel shelf has 2 4" speakers, and the trunk has an 8" subwoofer. All exclusive to the premium.
First, I moved the sound backwards until I reached a balance that compensates for the lack of rear speakers. Then I increased the midrange by 5dB to increase the power output of midrange sound to compensate for the less midrange speakers available.
Next step is increasing the lower end of bass to compensate for the lack of a subwoofer. The midrange bass should remain at zero because it only depends on the 8" woofer which is available on both trims.
An increase in the midrange treble compensates for the missing 2.5" immersive speakers and an increase in treble for the missing 1" mirror tweeters. They should probably be higher but I don't like a lot of treble, 3 dB is doubling the power.
I used 5 dB for the low end bass going to the woofers to compensate for their inefficiency in the very low frequency range. Theoretically they have as much power combined as the sub "160W" and 3 dB is doubling but they're not enclosed and probably have some bass blocking at 80 Hz.
I also used 5dB for midrange because it brings the immersive sound feature to life in the SR+.