I’ve done both predatory wardeccing and defending against it.
It is very easy to operate under a wardec, you just need some basic opsec. Competent corp leaderships teach this to their members - during a war where you are not intending to act as the aggressor, only PVE in cheap ships and clones (if at all), do not use hauler type ships without a scout and/or combat escort, and research your enemies to work out their strengths and their active timezones.
And most of all - when you can get the numbers, set a trap and inflict some damage on the aggressors. Have ten players in voice chat hiding in a wormhole that leads direct to highsec, and on the highsec side, fly a bait ship through. As soon as you are tackled, log in and score some brutal kills, then GTFO. Fight back and your predators will either fear you or at least respect you.
Current HS corps are so poorly run that these things which should be ABC of running a corp just don’t happen. Those corps do not deserve to survive.