If you're going to have a massive number of devices, I'd suggest something to hold them up on their edge, similar to https://www.amazon.com/Puloa-Detachable-Universal-Innovative-Removable/dp/B072KGL3VS/ref=sr_1_9?s=wireless&ie=UTF8&qid=1503968202&sr=1-9&keywords=mobile+device+charging+station

I don't know how much desk space you have, but you can definitely try building a shelf or something. The link is just to give an idea of what may work. I'd also suggest getting a multi-port charger rather than using that AC block, but as I said, I don't know how else you do things.