Plug the toilets and sinks.
Expansion joints for drywall are sold so there may be a problem with temperature, see
What's the coldest temp this house is likely to see (the 95% or 99% Outside Design Temperature for your area)?
How much are you likely to save in heating bills with the furnace set at 45F or so for several months (find a heating degree days Website listing your area)
the risk of damage costing you $???
with the risk of damage at 72F being "zero."