I'm in the same situation. I got stuck in England for 4 months due to COVID border closures and airline cancellations and worked remotely. I am barely able to make up the 4 months before my visa ends - I am short by around 1 week but this depends on holiday allowancss .
I have applied for CEC anyway and will submit my application as late as possible with a letter of explanation and see what happens.
I have applied for CEC anyway and will submit my application as late as possible with a letter of explanation and see what happens.