I have no idea what the appeals process is from overseas - I'm not sure that it has ever come up on this forum. My guess is that you simply submit the same paperwork as locals, but don't attend the panel hearing.
I think Etienne will agree with me that on 112 and 115 you are probably going to struggle to win an appeal, but if you have the advantage of not having to face the panel, why not have a go anyway? Put together your best case and post it off. I don't think the disadvantages you describe are necessarily mitigating circumstances, so put together the best case you have on academic grounds.
In the meantime, take a look at this thread (and the one that started it off, link is on the first post).
As you will see, RGS is a Foundation School which means that if they have spare places after the 11+ process (as happened this year) they can allocate them by means of their own entrance exam, albeit in the last week or so of August.
The size of the cohort this year is very similar to last year, so it is entirely possible that a similar number of last-minute vacancies will arise. How you take advantage of that, especially from overseas, is anyone's guess, but I would think that if you appeal and fail, a nice letter to the Registrar at RGS perhaps?
Nothing to lose, and everything to gain.