Thailand Elite announced the visa extension program two years ago. See the following thread on the topic.
I emailed Thailand Elite directly to ask about the matter, and their reply stated:
This is curious because the OP of the thread linked says TE at the time said:
Now either the person at TE replying to my email is mistaken about the matter or my situation is somehow different from the poster of the linked thread, as might be suggested by the hand written note on my visa. A possible explanation for the reason might be, is that when I transferred my visa from my expired passport to my current one, I used a visa agency to have to avoid going to Bangkok in person, and I thought that they had also done an extension of stay for me at the same time, but which wasn't done, so I had an overstay of 49 days which was then later fixed by me paying the full 20k fine, but I got the extension nevertheless, but only until the expiry date of my visa.
I will try to call them and find out for sure, though right now I am not very confident that I would be granted an extension beyond the expiry date of my visa if I were to enter the country before the expiry of my visa.
Yes I will be sure to call them ahead of time if I go this route instead of applying for the "visiting wife" extension as suggested by DrJack54.
Thank you for all the replies so far.