Bhante, another one of your essays come to my aid again (perhaps we should collect all these in a book!):
Seeing how you’ve raised the black flag on this term against all other translators, let’s dive into it. 
Thig 13.5:
Seeing fear in substantial reality,
Sakkāyasmiṁ bhayaṁ disvā,
I longed for renunciation.
nekkhammameva pīhaye.
I remember I used it before in Thig 8.1 & Thig 6.7 as well.
I find the arguments (& conclusion to substance) strong and the research is amazing, but the “Substantial Reality” too wordy and honestly, doesn’t it sound like a fancy way to say saṁsara (which is how the verse here reads to me)?
Like, I feel that refers to reality, for example, apples, chairs, cars, when it’s explicitly upādānakkhandhā in the suttas, composition of sentient beings and the wrong view of clinging to that composition as me? Something like avatar and avatar-view.
For me, there’s two points we need to satisfy:
- Sakkāya is five-clinging aggregates - this is right view.
- Sakkāyaditthi is wrong view born of clinging to aggregates, abhinivissa into aggregates, kind of like the opposite of anatta.
I think Constitution or Composition fit the bill. Former might be confused with law - but I like Composition (or Bünye in Turkish).
Interestingly enough, these are words you’ve never used the word in the suttas, Bhante. 
Also, V. Ñānamoli’s “Embodiment” is another interesting translation, IMO (another word you’ve never used!).
I agree with V. Bodhi that it’s darn hard! 