How to use pathfinder to make a mask

[abc-illustrator-fan]

There is a linked raster underlay in my artboard. I would like to create a solid white region over unneeded areas ofthe raster image.

Can I use the edges of the encompassing vector objects to quickly create a fill to cover this?

[Monika Gause · Accepted solution]

THis looks like a complex artwork. And while it is possible with SHapebuilder tool, I would probably not do it with such a complex artwork. Just clicking a couple of times with the pen tool should be less painful.