When LocalFileAccess is false, the default target is about:blank and there is currently no way around this. When LocalFileAccess is true, it randomly generates a file HTML which is then loaded in the browser.
So to further customize this, we added
function GetLocalAccessFileName: string; virtual;
Which allows you to override this. This would mean you need to create a descendant class, specify the full file name and path where the maps HTML need to be saved. Would that be something you can work with?