Hia Janine,
From my experience, cats don't run to schedules that we try to impose
! Last night I went to visit a friend in the next road and Oscar came with me. I only stayed a few minutes to chat but during that time Oscar sat outside on the step and yowled until I came out. When he wants to go outside, he yowls until the door is opened. When he wants to come inside he yowls until he is let in. (Sometimes he changes his mind and sits at the door, thinking. It drives my husband mad
). I can just imagine trying to explain "sorry you can't go out until xx time Oscar" or "you have to be back home by xx time". Hehehe. "Aye right" his eyes would say. "Rules don't apply to cats". And he is just an ordinary tabby cat. I can just imagine trying to persuade a Bengal cat to stay in or go out according to his owners wishes, and having to listen to his voracious protests for (probably) hours, until he gets his way.
I have thought about fencing, but our garden is enormous and the cost would be prohibitive.