The nice thing about the Optimas are that they don't vent explosive gas like conventional batteries, so inside mounting is a breeze. A battery box is still a requirement to secure the battery and help prevent anything conductive shorting the terminals. A good location would be the rear-right corner below where the lug-wrench is stowed. You can easily route your cables underneath that interior panel and mount any isolators or controls in the lug-wrench compartment for easy, concealed access.