we are similar, but have made small headways. Ds is almost 3 and is slowly starting to understand that he should be in his own bed.
We have to be persistent in returning him to his bed, but there is a cut off time, when the sun comes up, he is allowed. If ds stays asleep all night we don't see him, so maybe address the issue as to why he is waking in the first place? hungry, thirsty toilet etc etc
I did make a point of buying him a king single bed so one of would fit in with him.

One of our biggest problems was getting him ito bed in the first place and getting him to be happy to be there, most days one of us reads until he falls asleep, which sounds extreem but he gets maybe 2 of his books, and then at the moment he is getting harry potter, he's already had the hobbit, whatever my husband was reading and fanastic mr fox, about 2 pages of a non picture book does the trick.

my ds also has a serious touching skin fetish that I have been slowly trying to wean him off, last time I put him to bed, i sat down the other end and he was allowed to touch my ankle, his favorite place is my tummy