If I am using Closer to Tabletop mod, how will ranged Sneak Attack and Arcane Trickster Sneak Attack spell works?
Sorry I am not familiar with the pnp system
With that mod you need to really flank enemies to get flank bonus. That means have one of your troops on opposite sides of your target. Your ranged sneak attacker will still be able to get sneak attack in that case.
Or you can start dangerous combat with Octavia in stealth so you get first attack as sneak no matter the flank and then cast improved invisibility to get sneaks for rest of combat (and use quicken rods later when you have those).
You can also use Impromptu Sneak Attack - up to 4 times per rest. Vs most enemies also Invisible Thief will work - similar effect as Greater Invisibility, but you can enable it as a free action and use for any number of rounds you need it (as long as you have charges left).
Lastly, you could also pick Shatter Defenses for Ranged Touch Attack spells - provided that your party supports putting enemies into Shaken state (Bard with Dirge of Doom in range, Dazzling Display/Dreadful Carnage on a character with strong Intimidation, Fearful Aspect caster in range, Dragonform caster in range).