@Dylan ******
In fact there are other visa where it works that way, like a normal 60 day tourist visa, when you enter just before it expires you get 60 days and can get an extension of 30 days.
But every visa is different, so just like you I doubt if it will work.
When I hear stories about extensions being difficult always for DTV, I cannot imagine they will extend in this situation.
Apart from that a lot of DTV holders don't comply with the visa requirements anyway, so they never get an extension.
And when you comply with requirements, just get a new one is cheaper if you plan to use for another 5 years.