Found a link that helps with the estimate.
So, lets play.
Doing some digging into other article-like tables I have, I've found the longest article to be about 4000 characters in length. I'll assume all of the words are unique, and none of the words are noise. Lets say every word is 5 characters. So, there are approximately (4000 / 5) = 800 unique words or tokens.
The longest title, 70 characters. Using the same logic, (70 / 5) = 14 unique words or tokens.
The simplified index structure, as shown in the link, indicates that there are additional columns for tracking columns, documents, and occurrences, along with additional columns not shown. In this crazy example, lets say 10 integers, at 4 bytes a piece.
5 bytes per word + 40 bytes for index details = 45 bytes per record
45 bytes x (800 + 14) records = 36,630 bytes total per article
36,630 x 200 articles = 7,326,000 bytes
Which is approximately 7 MB.
These are all rough numbers, especially as I'm unclear on how many additional columns there are, how the compression works, etc. Even if I'm off by "a long shot", it's still likely less than 10 MB. I think I can spare that.