Kudos to Money4Nothing, that actually works.
Simply create a UDT that contains a bool array of whatever length you need. Create two tags of that UDT type. Leave one populated with zeros. When you need to clear, COP the empty one to the working one.
UDT name bool128 as an array of 128 bools. (I named the element bool128 too)
my_boolarray as type bool128.
empty_boolarray as type bool128.
COP empty_boolarray my_boolarray 1
Should do the trick.
The tagname may look a little odd...
Instead of my_boolarray[0], you get something like my_boolarray.bool128[0].