Hmm Linke, I downloaded the martian and bender skin. There are no infos about the hitbox size included. Thing is, if hitboxes are smaller, it would be unfair for players using other skins. Especially, I suspect the martian skin to have a smaller hitbox because the author says that this skin IS smaller than usual skins.
Another problem is the customisation: The more skins (or other customisations) the more files have to be downloaded from the redirect server i.e. the more time players will need to join (btw more traffic=costs...).
That's why I can't follow every players wish for customisation - the server would become unhandy.
But nonetheless I'm curious how to install and if it works

So I will install one single custom skin. Because of the hitbox size, it will be the bender one. To install it, the server has to be restarted and the MD5 database to be updated. I won't do this while players are online, I have to wait for off-times
e.g. sunday morning.
greetz, heinz