You'll need to enable Developer Options on the tablets, but after doing so, use the following setting.
Settings > Developer Options > Device hostname
This will allow you to change, obviously, the hostname that the tablet uses. You'll want to reboot the tablet to ensure it refreshes properly on the network side. However, not every device may have this option. If you don't see it after enabling Developer Options, use the following method, though it will require root access. You should be able to unroot without having the hostname reset, but don't quote me on that. I'd give it a try with the first tablet to see whether or not it will work.
Install a terminal emulator on the tablet. Enter the following:
Code:
> su
> getprop net.hostname
> setprop net.hostname <new_hostname>
The 'getprop' command will return the current hostname, so you can double-check it before setting the new one. Again, reboot to refresh network assignments.