a more neutral term (two cents)
I'm partial to "proletarian." Or even "plebeian," but those might make the OP sound like a snob.
[/irony] ;-P
I think a language change isn't going to change any attitudes. I'm inclined to allow posters who use the term "trailer trash" enough rope to hang themselves. The term is so loaded, that substituting "working class" bleeds out some of the information in the name opinions. Just commenting that it's judgmental, is probably enough to counteract its contagion. And someone nearly always does.