I found a quick and dirty fix for the time being, I don't think it breaks AAI too much or your mod.
In the Entities folder there is a file called entity-updates.lua, AAI modder made changes to the code so that any vehicle can be controlled by AAI, and to create balance between all the units they limited the weapon number to 1, and assumed that the last weapon would be the best one.
That is why it appears the rocket launcher is the only weapon usable when running Heavy Tanks and AAI. Here is the relevant section of entity-update.lua
" -- only 1 gun per vehicle
if vehicle.guns and #vehicle.guns > 1 then
-- assume last gun is best?
vehicle.guns = {vehicle.guns[#vehicle.guns]}
end"
I simply changed the number of weapons from 1 to 3 in this line "if vehicle.guns and #vehicle.guns > 3 then" using notepad ++.
Now my 6 playthrough of the game I'm able to clear out nests with ease rather than using tons of AAI vehicles or placing turrets down to clear nests.
In the code there is an exception to remove AAI options in entity-update.lua starting at line 248, not sure if that will help but it deals with specific entities like nixie tubes. Then your tanks will be completely excluded. I still haven't found weapon exceptions for specific vehicles.
And as for hovercraft, I haven't seen anything related to water splash, but I mentioned it as it might give a hint to how "classes" of vehicles are coded into the game.
Hope it helps, your mod is super fun!