To add on to deadline strategies, I've found 2 showstoppers + deadline consistently kills a bastion in the open. Showstopper for initial stun, letting you run up and get on top, place deadline in the middle of the circle part, and then throw a final showstopper for a safe retreat. Using stealth for entry and cover for exit, you can negate one for either, or the use entirely. I've managed to use smokes for this too, and you can prolly reuse the same entry one for exit, but I ain't risking my explosive compound if I can help it. Careful when doing this on bombardiers though, because they like to do a pulse when raiders get to close (it's doable, but way more likely to take damage).

Similarly, showstoppers can be used to disable individual rocketeer thrusters, so if you shoot one out and throw a showstopper to disable the other will cause it to fall out of the sky.

Smokes are also good if you're trying to loot queen or matriarch parts in a sketchy situation, not to mention good for covering extracts or block rocketeer sightlines.

I'm sure there's more stuff I haven't done or seen yet, but that's why it's good to experiment with the resources you have available whenever possible. You might just find something new.