Matt,
What year is your boat?
An 1/8" is too much to leave alone.
I would use 3M marine filler. It is Vinyl Ester and glass spheres. This equates to low moisture absorption potential which is good for the bottom of a boat.
I will dig up some pics of the bottom of my boat. There was a large depression about two feet forward of the transom from the outer strake to the keel. I believe the Stbd side was 1/8" max and the Port side was up to a 1/4".
I had to add glass on that side.
Don't hesitate to ask questions.
Jeff
" Just piercing the surface"