Bike security in a lock up?

Hi All. My last bikes were kept in my garage, chained, with the garage alarmed to the house. However, I now live at my girlfriends with no space for my new T’Cat, so it’s now residing in a metal shipping container on a generic storage site. My question is, do any of you do the same and if so what security measures do you take? I can’t use a ground anchor and the metal loops on the inside are a little small for a chain. Technology has moved on and the scum now use battery powered cutting tools. Any help would be of help as the brown hole is getting a little twitchy.. Even if it’s a decent chain or something.. TIA..