I found this site. It has a good amount of details on Alien and the others.
https://alienseries.wordpress.com
Searching around the Internet, apparently a lot of people have the same questions. Mostly coming from the bad sequels and videogames. I think the approach to take is similar to the newer Star Wars movies. These sequels, video games, etc. are made as product. Most of the time without the same care as the originals.
But I am rethinking the distance to that ship from the colony, I watched the cut scene on youtube and it seems like the guy sent Newt's family and others out and they were gone for a week? The truck isn't a small thing either.
Still I believe in Ripley's competence. For example, if someone knows that bugs are a house and they originated in the basement but they spray outside and around the house and remove some bushes. The basement is still intact. I think Ripley knew where the ship was in relation to the colony. She knew that the resulting explosion would be enough to destroy the colony and ship.