I will go over the process better on the passenger side (due to better pictures). But you can see here where I marked my cut line about 2.75" inside of where the inner wheelhouse would be mounted
Then with the help of a cutoff wheel / Plasma / and sawzall I removed the necessary metal. (This was the first cut... there is MUCH more trimming and cleaning up done before the tub goes in.)
Here is the passenger side tub being trial fit into it's location.
