I can suggest a handful of pointers for RC.
First, in feeling that you're picking answers that are "not the most 'exact'" in comparison with the correct answer, it's important to try to confirm every answer you choose by being able to go back to the passage--ideally to a specific line reference--to verify your reasoning behind selecting the answer. Often students will try to answer questions (on reading comprehension and also logical reasoning) based solely on their vague recollections of the stimulus/passage; while this can come with the benefit of saving a test taker time, it can also make some questions more perplexing and time-consuming. It's best, if possible, to take that quick extra step of confirming one's answer choice by going back and finding explicit support from material in the passage.
You also mention choosing answers that are "out of scope." Perhaps one worthwhile thing to keep in mind is the type of question you're answering. Offhand, a parallel the reasoning type of question is a type that comes to mind that usually comes up on one or more of the passages and could involve an answer choice that brings in new material. Also note that must be true questions form the bulk of reading comprehension; thus, there might be plenty of "minor leaps" (i.e., inferences) that these questions could test. Working on diagramming conditional reasoning that you encounter on reading comprehension might be helpful in seeing these.
Lastly, you write,
I oscillate between picking answers that are too "exact" and answers that I think aren't "exact" enough
On this point, it would probably be helpful for you to track more specifically which types of questions that you are getting wrong more often than others in reading comprehension. Perhaps "too 'exact'" means that you gravitate toward incorrect answer choices that contain much of the language/subject matter as in the passage (but are wrong for other reasons), and not "'exact' enough" refers to those that end up being right but seem to general (like ones about the overall structure of the passage). In either of these cases, I think the best advice is still to go back to the passage and point with your finger/hover with your mouse over the part that justifies your choice. General notations you made while reading the passage will hopefully help with questions involving more broad answers. I've suggested to students taking the Flex test, since it only allows for highlighting, that they might find it helpful to make boxes to denote each paragraph on their scratch paper and making rough notations on that.