Question about U+170D, which I hope will become TAGALOG LETTER RA

[Fred Brennan via Unicode]

Greetings,

I write this letter with questions regarding a proposal I hope to make for the 
encoding of TAGALOG LETTER RA, which we locally know as the baybayin letter 
"ra", at U+170D. Many fonts are already using this unencoded codepoint for 
TAGALOG LETTER RA in breach of the standard. TAGALOG LETTER RA looks like 
TAGALOG LETTER DA, U+1707, with an extra stroke. For examples, see Norman de 
los Santos' Unicode baybayin fonts.[2] Paul Morrow's fonts, which are used on 
the Philippine peso, also include "ra" outside of the ones meant to be exact 
digitizations of the first baybayin fonts.[4]

I had previously assumed that this space had been left open in anticipation of 
the future encoding of TAGALOG LETTER RA, but that this hadn't happened due to 
apathy; however I've since been informed that the space was left open as an 
oversight of sorts, considering that four Philippine scripts were encoded at 
once as a result of WG2 proposal N1933.[1]

I hope to request this as the Google Noto developers will not follow the de 
facto standard unless it is given the Consortium's approval.[3]

My questions are:

• How old do I need to prove the letter is? Baybayin "ra" is not used in 
writing Old Tagalog and is not used in the earliest Tagalog texts. However, it 
certainly has existed since at least 1985,[4; under heading Bikol Mintz] and 
perhaps decades earlier.
• May I use signs and fonts as evidence? What types of documents may I use?
• Would anyone volunteer to help me write this proposal, or check it over 
before I send it?

Thank you.

 [1]: https://www.unicode.org/L2/L1999/n1933.pdf
 [2]: http://nordenx.blogspot.com/p/downloads.html
 [3]: https://github.com/googlefonts/noto-fonts/issues/1185
 [4]: http://paulmorrow.ca/fonts.htm