PHP and jQuery customisation

I need someone to modify the backend of a Themeforest theme for us.

It is a holiday rental booking platform.

Currently the options, when booking, are nightly, weekly and monthly.

Our client wishes to only offer Monday - Friday (check in Monday afternoon, check out Friday morning) and Friday - Monday (check in Friday afternoon, check out Monday morning) as options.

We also require the calendar on the website to automatically "drag" the date to this corresponding date availability. So, at present if they click on a day, the day rate comes up, we would like to calendar to automatically highlight the Monday - Friday option (if clicked on a weekday) or the Friday - Monday option (if clicked on a weekend) and calculate the total fee. The image "cal" is how we would like it to look (functionality-wise).

A couple of screenshots are attached, however I'm happy to provide more information and access to the site for anyone wishing to explore further.