I found a place where I could access both the back and bottom of the safe from the other side of the wall/floor. That way I was able to put large pieces of aluminum plate to make it much more difficult to rip out.
Use carriage bolts with the self locking nuts inside the safe and just cut off the excess tread.
Mine happened to be under the TV in a small cupboard.
Hope that helps.
Happy Glamping, Norman & Elna. 2008 Winnebago Adventurer 38J, W24, dozens of small thirsty ponies. Retired after 40 years wrenching on trucks! 2010 Ford Ranger toad with bicycles or KLR 650 in the back. Easy to spot an RVer, they always walk around with a screwdriver or wrench in one hand!