You have a T code from your time as a UPT instructor, right? Then you have nothing to worry about if you don't have your K code yet for your MWS. I know people who were copilots for their board, and as long as they showed good progression within their primary duties, it didn't matter a bit that they were not an AC or an IP.
Consistent MAF O-4 and O-5 board feedback shows the following in order of importance:
1) Appropriate progression in primary job performance (i.e. MWS FP->MP->IP->so on or UPT IP->MWS MP->so on).
2) Appropriate progression in secondary job performance (i.e. no additional duty->mobility->SELO->scheduler/mission controller->chief of x->etc). Strats play in to #1 and #2 on this list.
3) Appropriate PME complete (SOS any method for O-4, ACSC any method for O-5).
4) AAD complete (N/A if you have a DP to O-4, very good to have if you have a P to O-4, pretty much required for O-5).