Home alone for 4 days

Hey, first time cat dad here. My cat(1 y/o spayed female) will be left alone at home for 4 days due to a family trip. She will have access to an outdoor catio to play and watch birds. We're planning to set up multiple litterboxes for her to use throughout. Shes skinny so she has constant access to dry food, and we'll have a known person(as in, the cat is familiar with them) visit twice a day to feed her and play with her for maybe an hour or so.

We tried a pet boarding place for a day and she came back miserable, smelly and with pee all over her. She also spent the entire time at the boarding place in a closet, refusing food, water, or even treats. The 2nd boarding place we booked cancelled on us, and the trips coming up in a week or so.

Im kinda nervous since shes used to having someone around all day. Does this setup seem alright? Follow up, is it recommended to take her to the vet once after im back from the trip?