Trying to plan out a trip to Serbia in late May. Broadly speaking wanted to check with people in the know about whether it's better to go with Airbnb with a "base" in a town for 2-4 days and do day trips, or driving and switching accommodations every day?

Broadly speaking was hoping to do:
Belgrade 3 days - is this too much or too little time to see the main sites? I would try to also see Zemun and the Vinca site
Vojvodina 3 days - Novi Sad, Fruska Gora park and monasteries, Sremski Karlovci and Mitrovica (Roman ruins), and Subotica and Sombor
Eastern-Central Serbia/Danube 3 days: the Iron Gates, Smederevo fortress, Golubac fortress, Lepenski Vir, Manasija, Kalenic, Celije, and Ravanica monasteries, Zajecar-Felix Romuliana
Southern Serbia 2 days: Nis, Remesiana, Mediana, Stara Planina, Prohor Pcinjski monastery
Western Serbia 3 days: Zlatibor, Zica, Mileseva, Ljubostinja, Arilje, Djurdjevi Stupovi, Studenica, Sopocani, Gradac monasteries, Novi Pazar, Stari Ras fortress, Maglic fortress, Uvac canyon/Tara national park
Last day drive back up and stay overnight in Belgrade and fly out the next day

Does this sound reasonable/feasible to do?

Also I may or may not be traveling with a limited mobility travel partner. If she needed a wheelchair, are any of these places reasonably wheelchair accessible?

Thanks all!