Question about Fail-Safe for a RDWC system.

I'm putting together an RDWC system but am the paranoid sort and so am afraid it'll fail while I'm at work, flood & completely ruin my floors before I make it home and realize there's a problem… I'm looking into a flood tray (like pictured) to put under the 4 plant set-up in my tent and then a smaller one to go under my external reservoir outside the tent to hopefully save my floors if the worst does happen. The flood table has 7" sides on it, which will be needed in the worst case scenario, but my system utilizes undercurrent. Can anyone recommend a riser? or something durable enough to set the system on inside the tray so it sits high enough that the 7" wall won't be getting in the way of the PVC running to the external reservoir but that also low enough volume that if the system failed the riser wouldn't displace enough water to cause the flood tray to overflow rendering it useless? Or has someone else already invented a simpler solution & I'm just overthinking this?