I think there is a bit of confusion here.
Show organisers expect Living History Groups staging displays to have Group PLI. PLI is also part of the exemption for re-enactors to buy replica firearms.
An individual vehicle owner who decides to wear a uniform to compliment his vehicle does not need PLI.
If you are going to wear period uniform I would just ask to people to take it seriously and do it correctly and with respect. If you are to old, to fat, not willing to buy period eye wear (if required) or have a hair cut/remove any inappropriate facial hair, don't do it.