We had to transition our 18 month old son after he flipped out of the crib! Scared us both - our oldest never did that! Ugh.
We took the front side off the crib and are using the crib as a "day bed". We did this with our daughter and then put her in a regular twin bed after a few months. During this "transition" time, she had to sleep in a double bed at a cabin we rented and she did just fine - one side was against the wall and I moved the side table away from the open side, just in case. I was more anxious than she was and we had no problems. I did put pillows on the floor the first night though. LOL.
For training purposes, we used a safety gate across the doorway to keep the kids in the room at night. My son spent the first few weeks sleeping on the floor in front of the gate because he did not want to go to sleep and would stand there and protest till he basically passed out from exhaustion. We would just scoop him up and put him back to bed. Now, he is actually falling asleep in the "day bed". I cannot wait to get the other twin bed down for him! Maybe around his second birthday...
Ultimately, you need to make a choice. I do not think keeping both items in the room is good and that it is probably confusing to the toddler. The safety gate works or if he is used to having his door closed at night, do that. Just be consistent.
Good luck!
~C.