I am curious about attaching a shelf to my hot tub. My Sundance Maxxus has the big filter cover and that works OK to set things on like drinks. But often times my wife and enjoy wine and take the bottle out with us. What does everyone do? Do those shelfs that screw to the outside of the tub work OK? I don't like the idea of screwing in (into) my tub! (No Pun Intended You Sick Buggers)