H1B amendment for temporary work assignment


I am on H1B visa with employer A working at client location B ( Dearborn,MI) but since Covid have been working from home because offices are closed
I will be on temporary assignment from Apr, 21- Dec, 21 and require to travel to and work at location C (Louisville, KY) for product launch and would be back to Dearborn after assignment, I will be travelling to residence in MI on weekends every two weeks . All expenses of travel and accomdation will be reimbursed by client

Can someone please let me know

  1. If a H1B amendment required as it is a temporary assignment
  2. I am planning to travel for initial H1B stamping in Dec,21 and would like to avoid amendments taking into consideration processing times of amendment
  3. Can I request and employer to provife any supporting docs that would specify temp assignment and would not require amendment, if so please advise what docs