Having control assign a Domme partner to help him from mission to mission, and "break him out" of some scenarios could also accomplish your goal of transportation and safety. In a twist at the end, said domme might even change teams and betray the subbie to the evil domme In the penultimate session. I am sure a few subbies would volunteer for this duty as well...schedule permitting, I certainly would!!! Good luck, this sounds like it will be a wonderful session, mostly due to the creativity and preparation you are putting into this, he is a very lucky subbie indeed!!!!