Here are a few pictures of a rack that I made that I consider hot safe. It is a lidded rack system and the lid is held on by the cage sliding into a metal channel, so there is no way that the lid can be lifed off of the cage while the cage is in the rack. For more security I've thought about running a locking bar across the rails... (and it is heated with belly heat)





. I like your efforts though and I agree with how it offers a better situation than an open top rack. Looks nice.