Teleport sleepers instead of using CanNetworkToSuggestion
Instead of using heavy 
CanNetworkTo​

hook you can try to teleport sleepers out of map bounds (or just in sky), and teleport them back on logging

The plugin name is Invisible Sleepers, doing that will completely change what it is supposed to do :p
In response to Tricky ():
The plugin name is Invisible Sleepers, doing that will completely change what it is supposed to do :...
Will other players see them? Nope, they will not
In response to Orange ():
Will other players see them? Nope, they will not
yeah but what you said will end up being a heavy plugin, using CanNetworkTo is better than making a plugin like that imo
there is another option which is kill them and respawn with the inventory
In response to Tricky ():
yeah but what you said will end up being a heavy plugin, using CanNetworkTo is better than making a...
There are differe between smart and useless actions
I am already aware of this and will soon change it. Either tping or killing them saving their pos and inv. Thanks for your suggestions

Merged post

The thing is this is intented for a modded build servers of any kind, which means most likely people will be able to noclip around. They could find the bodies sleeping somewhere so I will most likely go with the killing and saving all data about them
In response to collectvood ():
I am already aware of this and will soon change it. Either tping or killing them saving their pos an...
You can just spawn sleepers very high in sky. Position like

X = <random: -mapsize-mapsize> 
Y = <random:1000-9999> 
Z = <random: -mapsize-mapsize>​

 I am sure that nobody will find them, because they will just doesnt know that they are somewhere there.