Traci, ok here's what I did for David that seems to work, especially after a horrid night of regression.
I would keep nap at normal length, even if more overtired, someone here told me once not to let them make up night time sleep during the day. And then go with the early bedtime. I know you said it is hard with coming in so late, but cut out some stuff that isn't necessary, just until you guys get it right. We have a hard time with early bedtimes too, but it is well worth missing something that isn't a necessity to get an early night to do it.
Then, the big thing, even though you think it might be faster just to get him to sleep, REMEMBER, it's not to go back. It's never faster to go back! Stand your ground, stay at the door, if that's where you are at. I found that I am usually pleasantly surprised if I can hold my post, so to speak. And you know what, even if staying at the door would have taken the same amount of long time that it took to hold hands, you would feel good about making that progress and staying. And Cole would've learned that you are there for him, but he can do it on his own.
You can do this! Cole is so smart and he knows how to get you to do what he wants. When you are starting to waiver, remember how proud, not only you were, but Cole was to have that successful night in the his bed.
Start fresh tonight with a new attitude, knowing there is no reason to feel sorry b/c you are helping, not hurting. It's a new night, treat it as such! Good luck tonight!
I hope that helps! Kris