a general bit of advice for you two, as well as all others that do campaign/mission modding would be to jot down features of a mission prior to testing. i dont mean this for fun flights, but rather those in which you are checking out features youve created. this should help pinpoint issues
what type of install; what type of mission; aircraft; type of targets; number of targets; what is the target area; noting this info when testing and seeing what is different when it does or doesnt crash can help pinpoint the issue
yes, i know its QA/bug hunting 101, but a reminder couldnt hurt