Hi Lightning, sorry to effectively stalk you on here but a fairly simple way of fixing this issue would be to adjust the rifle soldier's 'sight' in rules.ini to the maximum size of a map (500 would probably do). This way, they'll simply see through all the shroud for the entire map, thus making it explored. You may need to adjust a few units to ensure you always have this ability, as not all maps may start with a rifle soldier but you could adjust on the go if need be.
Hopefully I am not too late and you didn't have to go through every single mission adding a reveal trigger.