JR East-South Hokkaido Rail Pass Enquiry

Hi, I am interested to do the tateyama Kurobe route one day I am in Japan. I want this to start from Nagano. I will be buying the JR East-South Hokkaido Rail Pass as we will be doing most of our travel towards northern Japan and Hokkaido. I have the Hokuriku/Joetsu Shinkansen covered only up to Sakudaira station. My plan was the buy a seperate ticket from Sakudaira to Nagano station but sometimes the trains from Tokyo to Nagano don’t stop at Sakudaira station and I am worried the ticket I bought for Sakudaira-Nagano won’t let me tap out at Nagano as I didn’t do the first tap on at Sakudaira station. Could you please help find a better way. Thank you for your help.