I've got a problem that may be unique,

A two foot section of house sill is decayed and is now gone completely
- located under the front concrete steps. Access from the basement is
difficult between the rafters but can clearly see the hole with the
insulation removed in this area.

I may have access thru a hole in the sidewall of the concrete steps.
Am not sure how big I can make the hole in the sidewall (there are 3
steps).

Solution......I don't see how I can scarf in a replacement piece of
wood due to poor access. Maybe fill with concrete somehow?

Suggestions?.........thanks in advance.

DHill