Hope I was able to explain myself properly
Have a look at these examples from Vorbly as they might help you with this design.
https://www.vorbly.com/Vorbly-Code/WIX-DAYS-BETWEEN-TWO-DATEPICKERS
https://www.vorbly.com/Vorbly-Code/WIX-DATEPICKERS-HOTEL-PRICING-CALCULATIONS
https://www.vorbly.com/Vorbly-Code/WIX-DATEPICKER-START-%26-END-DATE
https://www.vorbly.com/Vorbly-Code/WIX-DATEPICKER-START-%26-END-FROM-DATABASE