Heller DC-6 passenger window decal woes.

I'm building the Heller DC-6B in 1/72 scale and have aftermarket decals that go over and around the passenger windows . The kit has clear windows but the decals don't have cut outs for the windows. I assume that I will somehow have to cut out the windows after the decals are in place and fixed. Any suggestions about how to do this without tearing the decals ? Also since the cockpit has some seats and details but the passenger cabin is empty, am I better to black out the passenger windows from the inside?

I'd appreciate any tips.

Thanks