So if I understand correctly the switch has a 1 - off - 2 configuration and switches both live and neutral? In which case you can put the NE link on that switch between the inverter input N terminal and earth. That way, when you switch to shore power the NE bond will be released. You're right, without an NE bond the RCD won't work when on inverter power.
It will work but will have no trip reference. Consequently it won't provide the protection its fitted for.
If at all possible fit N/E strap at inverter. This won't leave any nasty surprises if the inverter is replaced in the future.