Your sling is the paper towel holder.  It is on one of the top cross bars.  Its easy for both the top and bottom to get to.  You can also put one on one of the front support bars.

When we travel, it can be difficult to contain all the lube in the hotel and we can't always travel with play sheets and such.  Flip the mattress in the hotel and play on that side.  When you are done, flip it back over to a nice clean place to sleep.

Next time you are in a bottom, closed fist, stay as still as you can and repeatedly and on the slower side, flex your fist.  Your thumb knuckle should be right at his prostate.  It will drive him crazy.   If you are coordinated enough, with your other hand, trace the outside of his hole gently while you do this.  You'll blow his mind.