How to handle arena equipment in 1.7.10 so it can't be taken away by players?

Using 1.7.10 version, I want to create a PvP/PvE arena. I want players to be able to get free equipment to play with, however, I don't want them to be able to carry this equipment home, because it will break the economy. Neither do I want to limit the total amount of times they can get the equipment nor players to be able to get advantage of "unauthorized" equipment that they carry from home.

The most straight-forward way to handle this is to have some large chests and/or an Ender Chest at the entrance, and have the players step onto a pressure plate that triggers a command block wiping their inventory each time they leave the arena (the passage is very narrow). If enough signs are put, players will understand how it works and not lose their things. Arena equipment is given inside, by activating another command block. I have seen this working on another server, but if a player fails to understand that his inventory is going to get wiped, he will lose his things. Also his things may get stolen from the chests if he doesn't use the Ender Chest -- which I don't want.

Is there any way, probably through plugins/mods, to replace player's inventory with something else to automatically restore it later?