You really can't - which is why the "test tone" approach is even used, but then it is not perfect.
So then you (the owner or tech or insert favorite tinkerers here) come in to try and make it right.
That is the crux of the problem - any stock radio is at the mercy of the last tech that tuned it (OEM).
So you can't even call it "stock" because of the minor differences in the component selection changes the result of what it could be . So they drag someone in to try make it "sound right" - you have to involved the human factor - and not a lot of them seem to even understand the roles Heterodyne plays in the SSB realm; for them to even know what they really do need to sound like.
Hence your problem and what you need to do to make it right.
That's is the hardest part - what do I need to do to sound right?
Each mode has it's quirks.
LSB is easier to work with because the coils inductive effects offset the LOWER side of the channel / Frequency. (Easier to use inductance)
USB - in light of the Cobra 2000/148's use a variable CAPACITOR to offset the rise you will need to correctly set the those same effects but in a HIGHER frequency range above the channel / Frequency. (have to add/subtract capacitance - has it's own quirks and sensitivities)
So to say "I'm using TP1" - well, then you set it, then someone comes along and sez' "your off" - to what?
There's the problem - to each radio - your radio will be different - it's not your fault they are, it is just that it does happen - so you need the "Human factor" to inject their own voice or other known reference to help clear up the differences.
On top of, did you truly set the Clarifier to STEADY 8 volt constant?
Might want to make sure your 8 volts of trimming is arriving to the board from that Delta Tune pot, is STAYING the same in both RX and TX.
You think I learned this overnight? Slept on a "Book of Radio by William Orr" so answers couid float up into my head in each night?
Heck no!

It took effort, applied, then retried and reapplied - to make the effort right.
You do your best to make it right - each time you tune you learn a little more for the next time to make it easier.
.