In the above screenshot we are ~north and looking ~south.
The triangular mountain in the distance is the same triangular mountain north of the city.
Trevor passes that rocket when he stood on top of the train, he is heading anti clockwise around the map.
He jumps off over the river seen in above screenshot.
The rocket is either located NE or E.
I said for ages that there is a huge range of mountains in the NE, consisting of at least half a dozen mountains and that Chiliad will be one of them.
I now think there could be as many as 10 mountains in this range.
It stretch from E-NE-N and the Alamo Sea will border all the inner mountains