Can you backtrack on a Shinkansen trip?

Hello guys, I just have a very specific question about taking Shinkansen and fare rules.

In short, I'll be taking Shinkansen from Sakudaira to Omiya, and then immediately backtrack on another Shinkansen train to Kumagaya. Time in between the two segments is about 6 min.

My question is if it's even possible to make such a trip with two Shinkansen reserved tickets (one for Sakudaira-Omiya, and one for Omiya-Kuamagaya).

If possible, which of the following three scenarios will apply?

1. No need to exit the Shinkansen gate, proceed straight to the platform for the other direction
2. Need to exit the Shinkansen gate but stay within station paid area. Re-enter Shinkansen gate with Omiya-Kumagaya segment Shinkansen ticket.
3. Need to exit the Shinkansen gate and station gate. Re-enter with new basic fare ticket and Omiya-Kumagaya segment Shinkansen ticket.

I know this might sound bizarre, but the reason I need to do this is because I'll need to travel back to Kumagaya, where my hotel is at, from Sakudaira, after the last Shinkansen train that makes a stop at Kumagaya departs. Also I'll be using the JR Tokyo Wide Pass, so technically I don't need a basic fare ticket to ride Shinkansen.

Thanks a lot!