Hey HJ so by way of update reinstalled and left out the bloodmoon server mod files that were packaged (as don't think I personally need them playing solo only). Plus I turn bloodmoon off. 
I don't know if or why that would be the cause of the issue I was experiencing with wild spawns but so far the mod has been behaving as it should be... no wild Z at all! 
EDIT: after testing above started new game and Z appeared in wild again. The only thing I changed in game settings was the city multiplier. I changed to "1" and I remember when first tried mod and got Z spawning in wild I had also changed the city setting that time to "2". I have since restarted game leaving that setting at 0 and have not had any Z spawn in wild so far. I wonder if that is the cause of the fault?