I'd really advice having a qualified electrician look at the situation. You are dealing with a lot of watts.
It sounds like you have two 30amp 120 volt shore power outlets with a parallel switch to let the genset supply 120 volt to both. Your air conditioners are also 120v (not 240v?). Are all 5 (!) air conditioners connected to the AC shore power outlet? Do you currently use two 30amp cords connected to two 30 amp marina outlets or do you use a "Y" adapter?
If you upgrade the AC outlet to 50 amp 120v (6000 watts instead of 3600 watts now) you would be able to run more air conditioners than now but still not as many as you run with the 15000 watt genset. This is a simple upgrade as mentioned by Birdseye. You would typically plug
into a 50amp 240v marina outlet and then use an adapter to use just one leg to have 50amp 120v. You could also use a "Y" to provide 30amp 120v to your house side and 50amp 120v to the AC (using two cords).
While there are ways to use two cords to get more than 50amps 120v to your AC this is quite tricky (for starters you have to use more than one marina power outlet).
Also, be aware that air conditioners draw about 2x their normal power when the compressor motor
kicks on. This can cause a shore power breaker to pop, especially if more than one compressor
turns on a the same time. Many air conditioner companies offer an optional control box
that has the compressors turn on one at a time. Unfortunately, this box really needs to be installed by a pro.