This is the most common type of commercial dumpster. As you can see, someone could not crawl into it. They would have to climb up into it, not the easiest of things to do even for a youthful, healthy person. You can't fall into them either, as they are about chest height.
No evidence has been made public as to how Wheeler got from where he was last seen on surveillance video, to approximately 5 or 6 miles away where the dumpster is believed to have been picked up. He could have walked, but he had no warm clothing, it was night or early morning, and the east coast was going through a very cold snap at the time. Whatever the cause, he clearly was staggering around.
So are we to believe he staggered 5 or more miles at night in dead of winter without warm clothing, then still had energy left to climb up into a commercial dumpster?
Additionally, the timeline made public indicates that most of the dumpsters along that route were either locked, behind secured fencing, or within sight of restaurants and apartment buildings. Most also had surveillance cameras pointed at them.
Are we to believe that, in his state, he still managed to find one of the few unlocked and out-of-sight dumpsters along that route?