Well I guess since I wrote the review I could throw in my two cents, lol! We have only used it on our king size bed. We haven't had any trouble with the fit. I'm Only 5'2" so the straps are plenty long enough, and the Velcro is strong! The cuffs are almost long enough to wrap my wrists twice....
If you are havin trouble with the fit, maybe try bringing the straps up from the sides if you have them over the top, or vice-versa. Make it work!!!