Thankfully, I just did the RC section on test 67 or I would have had no idea what your !Kung reference meant.
Can you be more descriptive or analytical in terms of what mistakes or difficulties you are having?
There's no way to attack an LSAT section by simply characterizing how many answers you're missing; we have to start getting more specific.
RC tests a whole bunch of skills / comes with a whole bunch of strategies:
- Can you comprehend what you're reading? (obnoxiously obvious, right?) Do certain types of passages bother you? If so, you can practice your reading chops, as you suggested, by reading comparably difficult material in the fields that bother you -- for some that's science, for others Humanities, for others Law
- Can you find the most valuable sentence or two in each passage? This would be the sentence or two that best encapsulates the author's main point. Depending on the passage, this most valuable sentence(s) could be a thesis statement, an opinion in a debate, a suggested remedy to a problem, an evaluation of a new discovery, etc.
- Can you easily, concisely, and accurately categorize the main point/purpose of each paragraph (what it says and how it relates to the big picture)? Do you remember this passage map vividly as you continue to work the problems?
- Are you familiar with the different RC question types? Do you have a firm command of each question type in terms of:
....
where in the passage should you look / what should you be thinking about before you start looking at answer choices.
.... what are the tendencies for trap answers for this question type?
- Do you regularly look back at the passage to compare the language of answer choices against the applicable line reference(s) in the passage?
- Are you good at locating the friendly keywords in question stems and in answer choices? Are you good at scanning a passage/paragraph and locking in on those keywords (or an equivalent paraphrase)? Does your mental Passage Map generally tell you easily which paragraph(s) you should consider for a given question/answer choice?
- Are you diligently combing the wording of each RC answer choice, primarily focused on what's WRONG/SKETCHY with it? Are you firmly attuned to extreme wording?
I agree that in re-doing tests you've done, you'll get an artificially inflating score, but remember that the point of practice isn't just seeing how you might score. It's about analyzing archetypes and tendencies ... gaining insight into your own mistakes as well as into how tempting wrong answers are written ... sharpening your reading instincts so that you can find the big ideas as you read a passage ... refining your standards of how close the wording in the passage needs to be in order to properly justify an answer choice.
I think, as you surmised, that just reading tough reading material and doing another test's RC sections is not great practice. If anything, though, do GMAT reading comp as a substitute, not ACT. If you bought an official GMAT guide, it would have the tight, professional test-writing standards you found lacking in the Kaplan (or anyone else's) fake stuff.
Ultimately, I'd rather have you doing LSAT for a 2nd time than anything else for the 1st.
If you have any specific questions relating to your weaknesses, let me know.
Good luck.