ornate sand
I wanna share what I think about the soundtrack, if game hasn't any radio music is fine for me, HLL 1 didn't have it and 1940s were the golden years of music but if you will add some music a cool option could be as in bad company 2 Vietnam various stations one for Vietcong (asian folk and propaganda) and other for Americans, in Americans you could name like "US Pirate broadcast" (which soldiers called Mars stations in nam) and include nam era underground music, there are tons of uncopyrighted/low copyrighted music from the era specially private press albums, not put only typical songs and of course nothing of AI music
the utopian would be an online radio station so the playlist would be infinite, playlist changing all months, game connected to a server but idk it that could cause lags, I have tons of suggestions but your experts I'm sure will assessment you well as in 2010 Dice had incredible musical assessment for Bad company Vietnam OST or battlefield Vietnam in 2004, specially bad company Vietnam featuring music from underground US and German legends as John O Docker from Frumpy, bad company 2 OST also featured some neo psychedelia of the moment by indie groups of the time but I would discard that idea for HLL because actual indie music s*cks and is very far away from 60s style
option D put in contact with the band who composed Vietcong soundtrack and convince them to make again their f"cking magic
the music can't be in a very high volume and in all vehicles because is not realistic, in battlefield as arcade game music was exaggerated like if apocalypse now was happening each day in real nam, and add script to avoid varios stations sounding at the same time