Simplifying parts of polygons in QGIS

Is it possible to simplify just the selected parts of a polygon? I am trying to make a simplified version of the Australian Local Government Areas (LGAs) shapefile.

I am using the v.generalise function from GRASS in QGIS, which works really well for internal boundaries. However, it often fails to simplify complex coastlines, and I’m left with hundreds of LGAs that area nicely simplified down to a few tens of points, and a handful of polygons with 10s of thousands of points, nearly all of which area along complex coastlines.

A quick solution to this problem would be if I could simply select the non-shared points along each of the complex coastlines, and use QGIS’s less careful Simplify function, but it doesn’t seem like it is possible to use that on only part of a polygon. I guess I could also break some features apart, simplify the relevant parts, and re-join them, but I’m not sure what would happen to my metadata then.

Anyone have any ideas?