1. We have a coffee van that has a generator and inverters each inverter 5kva peek 3kva constant each have a 220 Amh battery
2. Problem when we run the Oven (15amp) and the coffee machine (20amps) and the inverters (20amp each when charging ) they over load the Honda generator ( peek 7kva constant 5.5 kva )
3. Problem, complexity in operation
Instructions to the crew are
A. When using the oven turn off inverters 1 & 2 turn off food warmer ( food warm runs off the inverter we turn it off just to save the battery)
B. When cooking is completed turn off oven and turn on inverters and the food warmer

We are trying to simplify the operation of the van was wondering if you are able to help

 

Given the loads why didn't you put in a properly sized 12 - 15 KW generator to begin with?
Unless you got the batteries and inverters for near free the bigger genset would have been cheaper.

That said, what I would do is wire two devices that are not supposed to run at the same time onto DPDT switches such as food warmer and one inverter charger on one switch and the oven and other inverter charger on the other so that they cannot both be turned on simultaneously.