No Decay on Specific Toolboxes

Hey, we have a server that the admin team play on (Me and my girlfriend) and we want to build a few buildings out in the world for events (Like arenas and such) but don't want to have to deal with decay on them, I know there's a mod that lets admin buildings stop decaying - but we don't want our regular base to be protected by it because gathering resources is half the game, we don't want the unfair advantage.

 

Any plugins out there that allow us to set specific buildings to no decay and preferably un-destroyable?