Maybe try a very thin coating of contact cement? Actually some kind of industrial stength rubber cement might work or even contact cement from home depot (for tile) if you just use a VERY thin layer on the rubber and let it get almost dry before sticking to the plastic. Test it first on something similar that won't mind being marred, though. I fairly certain the rubber cement would be safe, but I'm not so sure how removeable the other would be. I use it to repair my shoes since its the only thing that holds under duress. Now that I think of it, maybe evn shoe goo would would work? (It doens't for shoes, but for that it might be quite effective...)