1c4 + rockets for the first room
1c4 + smoke for the last room (if u have to capture them, else you can just snipe them down from outside in a couple of turns).
Just be prepared to lose soldiers if you get within grenade range ...
I find alien bases to be quite easy tbh, you know where the aliens are and they can only come from one direction. Base defences are much harder especially if you get unlucky with enemy placement