Hi,
I'm using trail version of RadaeePdf, it working fine. But I need to add more tools like rubber stamp, file link, flatten, line, popup annotations.
Cordova and Xamarin plugins are distributed with full sources, one way to customize the UI and toolbar might be to customize Objective-C and Java source codes.
Try opening a support ticket www.radaeepdf.com/support and address it to sales.
Send the list of yuor requirements, better if you will send some mockups.