Simply head over this page and install the Text bookmarklet; running the bookmarklet on a webpage will display it using Instapaper’s parser, but it won’t add it to your Instapaper account.
They don’t say it on this article, but you have to do it on the desktop version of Chrome, because unless I’m missing something, I could not do it on the mobile version. I named my bookmark aa, when I run into a page where the font is too small, I just type aa on the URL bar, select the bookmark, and boom! I have an Instapaper version of the article where I can make the font bigger, change font, background color, etc. It’s a hack, and it’s not as elegant or easy as Safari’s solution, but it works.