Booking Calendar Customization

We have the Booking Calendar installed in its basic form. We want it to do more things than the current “out of the box” plug-in.

Schedule a showing calendar in sidebar, similar to:
https://www.estately.com/CA/Northeastern_San_Diego,_San_Diego#/listings/info/11125-doverhill-rd –
Needs to capture referring URL at a minimum so client can know what they want to see.

Anybody customized the current plug-in or know of another solution that we can work with?