This is what a washed out part looks like:
and (same spot, from the front):
from looking at fixing potholes online, it seems like filling it with a paver base and topping it with a couple inches of backtop repair might work, but I am not sure whether those work for the area this large.
What would be a recommended way of fixing this? I understand that repaving the whole driveway would fix it, but I'd like to see whether spending 35 times less and fixing it myself is also an option.