Riding to Sikkim on a bike registered in my father’s name. any issues?

Planning a solo ride to Sikkim soon. My bike is registered in my father’s name (Bihar RC), but all documents are valid — RC, insurance, PUC, my DL, etc.

Before I enter North/East Sikkim permit zones, I want to confirm one thing: Do army checkposts or Sikkim police create any problems if the bike isn’t in the rider’s name?

I can carry an authorization letter + owner’s ID if needed. Anyone done this recently? Any issues in getting permits for Tsomgo, Nathula, Zero point etc.?

Looking for real, recent rider experiences.