Every state is different when it comes to laws on vehicle lighting, but wherever you are you should be safe having purple high beams as long as you aren't driving around with them ON unless you're at a car show or an actual funeral.
Just to be safe, find an article online about "the silent siren" where this is explained that purple has always been the specified color for funeral lighting & keep a copy in your coach.
I ran purple high beams in the '67 M-M and Kevin ran them for years before I bought the coach from Ron with no hassles. They were very dark purple, almost looked blue when not lit. Also running red high beams in the '66 Superior ambulance currently with no problems and have driven it all over the place. Having a "silent siren" article with you seems like a good idea to play it safe.