How to set up a 2 night board so I get paid for both days?

First, you have to make sure the owner enters the dropoff and pickup times. In some areas, like mine, Rover is testing out charging prorated rates for exactly your situation. I forget, but I automatically get 50% more for a certain (maybe like 4-8) number of hours over, and 100% more if 8 hours over.

If that isn't available in your location, then you do it manually. When you see those type of pickup times relative to the dog's dropoff, then you modify the booking BEFORE the client has paid. When I have explained to owners that one night of boarding is only good for up to 24 hours of care, not a single one has balked or complained. It is only fair since you are watching a dog for two whole days. When we discuss this, I tell them that they would have to pick up their pet by 8 am on the last day in your example.

Since you already offer doggy daycare, you could just use that rate if the pickup is at time like 6-ish, which is within the range for doggy day care. However, if they pick up the dog in the evening on the last day, I would charge them for a whole day since it is over 8 hours,

We have certain hours that we're "open", 8:30am-8:30pm. Dog day care is limited to those hours. Dropping/Returning before or after adds a day. Boarding is 24 hours. We've tried "pro-rating" hours, but it's difficult to manage, as most of our clients do not know their EXACT time they'll be dropping/returning before the stay starts. Basically, we offer a four hour window after the 24 hour period before we start adjusting the rate. If they're dropping off at 9am and they return at noon... we let it go... if they drop at 9am and pickup at 8pm, we let them know it's $2/hr after 1pm (4-hour window), or a $14 adjustment.