From a system point of view the method for wiring
your switch depends upon the following:
Do you have an inverter/charger and, if so, what is the ac current
rating of the internal transfer switch?
Do you have a remote monitor
for the inverter which allows you to defeat "auto transfer" as well as "auto charge"? This has a bearing on how you might use the internal transfer switch if it is rated to carry the entire vessel current
Do you want the inverter to "serve" your entire ac breaker panel or do you have a "split bus" whereas the inverter output is dedicated to inverter-only load breakers?
Depending upon the above info you may only use your manual transfer switch to switch between gen and shore, making it easier to wire and more automatic.