Need help on mounting battery so IVA friendly....

[Eternal]

Hi all. I have got a nice small battery now that's perfect for what I need it to do. I want to try and mount it into the passengers foot well but need to make sure its IVA friendly. I don't want to drill/rivet through the floor but can weld tabs on if needed but could really do with some ideas on the best way to mount it so its good for the IVA test and also not going to get knocked around too much my passengers.