Chastity in vanilla life discussion

Hi everyone, My boyfriend, who is currently in his cage while I’m mostly at work, has just secured a new job. The position means he will be away from home (until we decide to relocate together again) for 5 days, then return home for 4. This cycle continues for 5 months. Since he’ll need to fly every time he leaves and returns, I’m looking for a way to make sure he doesn’t touch his (my, actually) man toy. He wants something that replaces the stainless steel cage, which is very comfortable according to him. The solution needs to pass airport security smoothly, stay discreetly hidden, and remain hygienic. I just want to ensure he refrains from playing without permission. Plastic chastity cages are out of consideration because we’ve tried them; they aren’t clean enough or comfortable for him (sometimes even causing pain and bruising by rubbing his sensitive skin). I considered letting him wear only black boxers, leaving unwashed until he returns home so I can check if he had erections or bad thoughts without permission. Do you have any other suggestions that could help or inspire me? Thank you in advance, @PrincesseL0uise