It's roughly the same method I use. For 4 layers I just sand paper the pcb (with water)...if you are gentle and wait long enough, the inner layers will reveal themselves.
Ouch. Sounds really painful, and also destroys the device. All the reversing I've done (in the last few years) was on devices I wanted to repair or mod, so destruction wasn't an option. And I have another one coming up (a big UPS) where I'll need to reverse engineer a couple of pretty large PCBs, along with the firmware. (Fingers crossed the binaries can be extracted.) That too is a 'no spares available' case, where I can't destroy the boards.
By the way, you always have the option to upload the files anonymously to some fileshare service (eg Mega) then 'discover them' and post the links to a discussion thread. But this way you don't get kudos points.
Something I would like to see, is reverse engineering docs for a variety of tablet computing devices. Of a vintage that is fairly recent (so decent graphics and CPU power) but old enough to be cheaply available second hand (or free.)
The aim being to jailbreak them from the original manufacturer's OS and end up with some Linux variant running only an open source cut-down browser. Allowing use as a general networkable display device via html5/Canvas/JS, touchscreen, etc.
Many tablet devices are really nice hardware designs, spoiled by stupid OS & apps gimmickry and corporate image bullshit. Would be great to be able to repurpose them as dedicated control panel things.
Or maybe someone has already done that?