Sorry to hear about your theft. After consulting with a technician. The white wires will be your grounding wires/negative. The Black wire is your positive. Now the green and tan wires would be determined by were and what they are running. If you have a power tongue jack or any other aftermarket product that required direct wiring, these probably are the wires for those items. If either the tan or green wire have/had inline fuse holders, these are both positive wires.
As far as securing your battery, the best thing to do is remove the battery. Out of site, out of mind. If you find this to be impractical, I have seen custom welded angle iron frames that go around the battery box. This type of set up is purely custom work.
Here is a 12volt battery lock I found online from BD battery lock. http://www.b-drvbatterylock.com/balocl.html
You could also use a piece of vinyl coated aircraft cable that fits around the battery so tightly, that it has to go between the vent covers on top or there is not enough slack to lock the lock. I know it's not theft proof, but considering how difficult it is to cut aircraft cable with bolt cutters, I figure it's a good deterrent.
Just some good ideas... to hopefully help prevent this from happening again.