Hi,
I was think that the Food Truck should have deliveries (like the Train Station in Farm Story 2) One you complete all the deliveries the Food Truck would drive away and come back a few hours later.

There could be 3 options:
(Level 45) Speed Run - Complete and earn coins and xps (1 hour)
(Level 60) Half Day - Complete and earn coins, xps, and 1 or 2 premium parts (4 hours)
(Level 75) Full Day - Complete and earn gems, coins, and gems (8 hours)

Maybe, it could introduce some new levels too.