NPCs make things a pain, but it is possible to RNG in areas with them. You'd have to adjust your advancements, basically, according to how many they advance. It's difficult to explain, though.
Ex. For fossils, the museum has one NPC that messes with you. Say my starting frame is 46, and I'm going for 60. I do my advances and end up at frame 64. Next time, instead of 14 advances, I'd only do 10, because I overshot by 4. Yeah, sometimes it takes more than one adjustment, but it's always worked out after them.
I recommend going for a Duosion on Route 9. At first glance the bikers look like trouble, but because they all move in set patterns, none of them will mess with you.