Ironically the warehouse of that contractor recently caught fire. Makes you wonder how it was heated. ;)

I have spilled water on the one warming the fishroom without incident - other than having to towel up the mess.

The one in our family room isn't working. Perhaps the best idea is to take in it - to whom I don't know off hand - and then lending it to you for the winter.

One water proof unit in a room (God help us, never use a room warmer with exposed heating wires!), a closed door, maybe that plastic stuff over the windows, might well be less expensive than 11 small tank heaters. It is a four foot unit and would have to be on the floor at munchkin level though.