IIRC, high BB makes it more likely to have CW. You can have it with 0 BB, but it is very unlikely (or unlucky). There are two ways to avoid BB, be in war or positive stab.
this map, just like in vanila, CW's are very common at 0 stability. only in mods like agceep, interegnum and maybe others this has been made impossible(or at least VERY unlikelly at 0 stab).
also getting CW can much likelly trigger if the country has a LOT of standing armies divided in many small contingents. for fun , try this: have only 2 standing armies(no matter their actual size) and remain at negative stab for a long period, i bet having a CW would be very unlikelly( would eventually happen but not as fast as if you have 10+ armies).bottom line, i have always noticed that the higher number of contingents i have, the faster i get a CW. with only 2 army contingents i have seen 20+ years while staying at negative stab, and NO CW (no matter the mod/map).
this aspect is much more obvious in "rome" and since they use some eu2 codes as well, make your own conclusions how this is possible and actually scripted.
BEST solution in mp, and the best calculated risk is to have a huge navy(albeit not all nations can afford it, but then again not everyone becomes a spanning empire). and then keep 200k-300k ONE stack IN the ships, and a 30-40k second contigent to deal with various local rebels. this works soo much better with higher naval LT. up to 3 contingents seems to have no effect in increasing CW risks, albeit the EXACT number of contingents present , in order to more likelly trigger it, remains a code "enigma" so far.
and then , in case of getting dowed you get +1 stability wich helps to calculate risks further....the 200-300k stack would definatelly buy you time by allowing you to struck decisevelly an enemy and thus avoid getting negative WS too quick , while getting above 0 stab and while making new recruitments , and this in the worst case scenario.