An excellent guide for Kamnik and Velika Planina is Irena Grmek. She would help you see the sites you want to see efficiently but also give you a lot of good information on what you are seeing. In Kamnik, I would suggest not missing the chapel in St Jacob Church that was created by Plečnik.
My comments on a day spent with Irena in my 2019 Slovenia trip report:
Irena in Kamnik. Irena and I spent a long but EXCELLENT day together at Velika Planina, Mala Planina, Bela Partisan Hospital, and finally, Kamnik. We had talked about my interest in Plečnik during the day. In Kamnik, she took me to a candlemaker’s shop to see if they would show me their still-preserved black kitchen. While there, she scored us an invitation to see a dining area in the candlemaker’s father’s apartment; the dining area was created by Plečnik himself for the family. It was spectacular.
I was with Irena from 9 am to 7 pm that day. I was going to cut out at around 5 pm after Bela Partisan Hospital, but Irena knew Plečnik treats awaited me in Kamnik and gently pushed me to complete our original plan. Oh my, I'm so glad I did.