What happens if you call Lester in a place where you automatically get a wanted level

What If found out so far:

how often does this happen?

It happens per in-game day (48 minutes). You have to pay it, even if you haven't been in your apartment.

You only need to pay, if you are playing GTA Online.

what happens if you can't pay?

You don't lose the apartment and you don't get locked out. What they do - They shut off your water and power, so you can't watch TV, use the radio or shower.

If you can't pay the mechanic, he won't answer your phone when you call him, so he won't bring you a car.

I don't think day/night makes any difference.

I've flown into the base multiple times (day and night) and have always gotten the same reaction. You have to fly close enough to the ground inside the base perimeter to trigger the wanted level of 4 stars. If you hover high enough above the base they do not seem to care.

In any case, it seems like landing a helicopter near a jet is the easiest way to obtain one.