ive had lots of those crashes.
in the end i figured out some things to make an 96km map.
start with a flat map, put start locations and some relais in, (the relais stations devide the map into Pieces or Zones)
if you have not enough zones the editor crashes.
and from then do render tests on quality 0 erosion 100
save map under different names to avoid not loading after crashes.
also try to avoid to high terrain differences, mountain to hill to flat is ok but mountain to valley sometimes crashes.
i have ordered some more 16gb memory to test more in the editor, hopefully with 32gb i can render with higher qualitys.