Tonight I am transitioning my 20 month old twins to toddler beds because one of them learned how to crawl (or fall, more accurately) out of her crib. I decided against the gate at the door because I was afraid the two of them could work together to knock it over or crawl over it, so I put a child-proof door lock on the knob. Surprisingly, it's been easier than I thought. After about 45 minutes of playing, crying, trying to get out, playing again...they are finally quiet! Not sure if they're sleeping or WHERE they are sleeping (my video monitor is acting up now, of all times!), but they are quiet. To me, that's a victory!
Maybe try a toddler bed instead of converting the crib. If his bed looks completely different, he might have an easier time with the transition. Who knows, maybe he thinks you "ruined" his crib by taking off the side?
Anyway, just wanted to say "good luck" and hang in there. I love this website because it just reminds me that other moms are going thru the exact same things that I'm going thru at this very moment! We will survive. As you said, he can't stay awake forever! (Although it sure does seem that way!)
Hang in there, Mom!