How would you (and the public) react if when the parks reopen, the visits are scheduled in blocks. For example, many rentals up in Cape Cod are check in on Sunday, check out on Saturday. Could WDW or Universal try to use some strategy like this to have a better idea of who's coming and going from the resort?
I'll use Cabana Bay as the example here:
Week 1: The left side of the resort (Continental/Americana) is open to guests, as well as the food court (mobile order), main lobby, etc.
Week 2: The right side of the resort is open to guests, as well as the food court, main lobby, etc. Meanwhile, the cleaning crews have a full week (or however many days the window is) to sanitize the left side of the hotel for Week 3's guests.
I'm sure there's many holes in this idea, so tweak as you all might see fit. One big problem that I see is length of stay. While some find value in an entire week at Universal, others may only see the value in 2/3/4 days. Perhaps each hotel represents a different length of stay? Or certain weeks are available as week long only stays while others are split into half week stays?
ie. June 7-13 may only be booked as a full week stay, but June 14-20 is split into two windows (June 14-17 and June 18-20).
At check-in, each incoming guest could be checked for temperature or whatever other metric that they use for sickness (at one of the unused hotel areas (Saphire Convention area?), sign any waivers needed, then make their way to their respective hotel. I think this idea minimizes the chance of day ticket guests coming from outside locations, and allows for things to operate a bit more smoothly within the actual parks.
The only outside "influence" would be employees, who could be tested each day at the start of their shift.