General spy-sat deployment (and to some extent smuggling) missions I've only been accepting when the objective is around a planet I know has some useful terrain to hide in around. After that, going dark and opportunistically picking the right time has overall worked for me; that said, it probably has cost me more in travel and supplies waiting for the right time than it paid when my fleets got a bit larger and I used the missions mostly as a means to increase reputation with the contact to figure out how/if that impacts the missions they give. Otherwise I've generally also found them more trouble (and time) than they're worth.
As for the Atzlan thing, I've completed it (sneaky like) three times over in different ways on my three characters so far:
1) I went in with a single phase frigate, but as KDR_11k remarks above I've since learned how the reduction in fleet profile actually works on phase ships; I'd never even read the phase coil hull mod thing and seen there's a reduction in profile fleet-wide for having that before very recently, since I used to dismiss phase ships out of hand as too expensive and too quick to run out of PPT in battle.
2) Pirates were raiding the system and the patrol flew off to fight some right as I was coming on up. Lucky freebie.
3) I simply patiently waited for just the right time in how the patrols were moving. A bit tedious, but it worked.
In all cases I had the T1 sensors skill, too, which obviously helped.