Sooner or later you will loose your ship, so better to include chance of a loss to final profit calc. I think if you have 1 loss per more then 5 days it is a acceptable result for any tier.
About T4 Gila, standard fit will not complete Karibdis + 6 Tiranos respawn. Confirmed several times.
One guy tried to add tanking drones, but failed to finish this resp. The only I can suggest here is to remove AB (useless module when you webbed several times) and fit one more Shield Extender, remove Shield Regen from low slot and add Ballistic Control or third Drone Damage Amplifier.
When AB absent, bot will not apply any of orbit settings from High DPS table and will always orbit Cache