export to .fpl in one step

[routeconverter]

Is there any way, that one single continuous route file to be exported in one single step, i.e. disregarding it consists of 3 WPT or 82 WPT for example?

Yes, for that the GPX needs to contain all the necessary information for the FPL file. Air Navigation Pro is said to produce such files.
The dialog in RouteConverter makes sure everything is inside so that for example a Garmin G1000 will accept the file and perform a reasonable navigation.