but when it comes to Guard Posts, bit of a problem: You could simply snipe every one bit by bit from far away and need never engage. If there's an idea to replace it that works I'm all for discussing it.
AIWC handled this via reinforcements: if I brought an artillery golem or built sniper turrets to destroy a guard post from safe range, ships would soon roll in to try and disrupt my attack, and on higher AIP the spawns from the command station would be a significant threat on their own unless I had something to defend my long range units.
And really, there was no reason to attack guard posts from up close unless they covered my entry wormhole or another vital objective, unless getting close was much faster and resulted in minimal losses (so using big units and/or taking advantage of hull bonuses), or unless I was too bored to wait for the anti radar dampening forces to be in position.
At the moment, even with 350ish AIP AI War 2 command stations only seem to spawn turrets as reinforcements, which makes slowly clearing out planets either a very low risk and low cost activity if entry wormhole isn't covered by multiple guard posts or if I have an artillery golem available, or a massive time and resource sink if the defenses can wipe full fleets in seconds and I have to wait for rebuilding before taking down another couple turrets.
Speaking of which, I've never seen a reprisal wave, even after losing ten mk2 bomber stacks in a matter of minutes.
I think throwing more ships at the player from the command station, scaling with the amount of guard posts on the planet, would be a good idea: that way one can snipe guard posts from far away while dealing with a large incoming fleet, or rush guard posts up close to get rid of reinforcements faster.
For things that can't move I don't see it as (as big of) a problem.
It's almost more annoying for static units IMO, as I can't even wait for them to wander into range or run away: so I end up with neutered planets growing a forest of tesla turrets near the edge of the grav well and there's no convenient way to stop that.
Speaking of which, neutering planets is far too easy: the command station and the warp gate never seem to spawn a significant amount of mobile forces (I think I saw a guardian spawn once, and that was at 300+ AIP), so a few sniper turrets near the edge and maybe some ambush turrets are all it takes to keep the area safe.