According to several sources (Klein, Hodge, Vernon, the jeweller who made the ring et al) Elvis did make a formal proposal to Ginger.
Charlie Hodge said he was there when it happened; as much as I doubt the story, there is no reason why he would have lied about it.
Other sources believe Elvis did no such thing. I'd suggest the truth lies somewhere in the middle.
Elvis "talked of" marriage with Ginger, but probably never formally asked her.
And if the story of the Christmas Day wedding is true, I think Elvis would've been talked out of it like he was talked out of the "hit" on Mike Stone. In any case, I don't believe Ginger would have been around for long; Elvis would've soon realised she was way too young and that this aspect of his mid-life crisis was bordering on embarrassing.
Ginger is a nice girl and - like the MM - has come in for way too much unjustified criticism from "fans" over the years.