At the back, I installed a TP (yes a toilet paper) holder - upside down - to hold my 2 bunk light/fans when travelling. I did replace the rod with a smaller one (an old curtain rod) as the other was a tad too large and made it hard to clip them.
I did lots of mileage - and they all stayed put. Never fell, fingers crossed.
As for the shelf right above, well that is a different story, with no guard rail, everything there kept falling down all the time.... I found a solution - went to Walmart bought a short telescopic shower curtain rod in grey. You set the length by screwing in & out one end. Works perfectly and now nothing falls down anymore