The aircraft will freeze but do not reset the Next Attack Timer. If you want to have an attack begin while you are in San Fierro then I would suggest:
Wait in a safehouse for 27 minutes and save. Next Attack Timer should be at 30,000.
Exit the safehouse, get in an R3 vehicle, and start the mission. Timer is back at 30,000.
Got to airport and cancel the R3 mission. Wait 16 seconds and enter the Shamal. Timer is frozen at about 4000.
Exit the vehicle and wait for about 1 minute for the next attack.
I don't think it will be possible to get Aztecas, or any of the other non-rival gangs, into any zone they are not already in. This is because the 3rd Kill Glitch switches the gang that is attacking, which determines the gang that gets the density increase, and also the zone that gets the density increase. The attacking gang will be the gang with the highest density in the zone where the 3rd kill occurs.
My earlier explanation wasn't entirely correct. You don't need to kill Ballas or Vagos in an Azteca turf during an attack notice to switch the attacking gang to Aztecas. CJ needs to be in the Azteca zone when he makes the 3rd kill, the Ballas or Vagos do not. At least, I'm pretty sure that's how it works based on my experience starting gang wars - and it's the same trigger, so it should work exactly the same.
You don't need to lose the attack. You could let it timeout. You won't see the Aztecas making the attack, but Aztecas get the density increase as long as the attack isn't cancelled or won. In the case of a timeout, +30. Remember that you'll need to win once in order to get a Grove density of 10 before Azteca density can be increased.
I'm having no trouble getting attacks to trigger when CJ is out of LS by setting the attack timer to a low value using scripts. I strongly suspect the attacks will also trigger under normal circumstances if you wait long enough.
I did not alter the gang cars in my tests of gang IDs 8 and 9. This is a fairly easy process on PC; just edit the appropriate line in the cargrp.dat file. Gangs 8 and 9 both have the Sentinel gang car, btw. However, someone recently posted the PC addresses for gang peds and gang cars in the GTA-SA memory address
topic so I've been able to make the adjustments to the gang peds and cars using memory writes. I suspect this is the same process that ric used for his PS2 mods. Since I prefer to avoid changing my data files I'll stick to the memory writes if I want to alter the unused gangs.Skin ID reference
FYI: I've always wondered why the car groups seem to be limited to only 23 cars. After examining the memory block for the car groups I understand why; there are only 23 slot available for each car group. This explains why the Phoenix and Euros are never available in random traffic despite being listed in some car groups. Which Zones Will Be Attacked?
Working with an old End of the Line
save I've got handy in which Grove has control of all normal turfs, I set the following zones to Grove 20 and Balla or Vago 20. These zones are listed in the order they appear in the info.zon file.
I ran my test near Catalina's place in Fern Ridge so these zones are distributed in a way that surrounds CJ and it is pretty easy to tell which zone is attacked from the icon's position on the radar. I alternated Ballas and Vagos to make it even easier to distinguish between the zones.
I set up my test script so when I press a button the Attack Timeout and then Next Attack Timer are cleared. Each time I press the button the current attack times out and another starts. As the test progresses the attacks start against the Quarry or Easter Bay (which appears random). Eventually the gang density of one or the other, Quarry for example, will roll over and attacks will be against Palomino Creek and Easter Bay until Easter Bay rolls over and is replaced by Blueberry. The pattern of either the first or last available zone being attacked continues until no more zones are available. Every once in a while one of the other zones is attacked, but this is fairly rare. Adjusting the density of the zones did not appear to have any influence.
Hypothesis: The next zone to be attacked will probably be either the first or last zone available for attack.