I have a child like your daughter, he hates anything to change and likes everything a certain way. All I did with him is talk up for a week about being a big boy and finally getting a big boy bed like mommy and daddy and his older brother. After a few days he was super excited, it just took a while to convince him it was a good thing.
None of my kids lasted in the convertible bed, after a week or two I just got them their full size bed. With my picky one, I didn't want to transition him twice so I just moved him right into his permanent big bed.
I am with you on the locking kids in their room and such, I just do not like the idea. I do however have a nighttime wanderer. My 2 year old daughter loves to get up at night, get out of bed and wander around. It drives me crazy, but the good news is the house is dark so she doesn't venture from her room. Just keep every thing dark in the house and she won't go anywhere.
With my daughter, we just let her get up and mess around instead of fighting it. Believe me, over time it happens less and less because they get tired. Just stick to your schedules and your daughter will do fine. You will probably lose sleep and spring break is the a great time to get over the hump but it isn't that bad.
Good luck!
P.S. If your daughter is not peeing in her sleep you probably won't have a problem with her at night. If she does every have an accident, she will probably freak out and it will never happen again.