If you all went and got a Lawyer to process your claim under the Wage Claim Act, the Employer would a Motion to Dismiss based upon Federal Preemption. The court probably wouldn't dismiss but would stay all proceedings until your NLRB caper was over. In other words, filing the Wage Claim Action now would be a borderline useless act. You win your NLRB case and the award includes or implicates back pay and you score that way. I understand the temporal inconvenience but this plan cannot come to any useful end for you.
I do hope your optimism is justified viz. the NLRB caper. Every Good wish.