Hey! Got a bit of an alternative view to EEEEEEP!
Though I didn't study two extension subjects, I did study two major work subjects - Drama and History Extension. Now I don't like to get into the whole "which is harder" debate too much, because at the end of the day it is subjective, and for the most part is case by case. But purely in terms of workload, I'd bet that Drama is more full on than EE2, simply because there are TWO major works rather than one (our drama teacher used to complain about how bad it was all the time: "its a three unit subject with only two units worth of credit!! The IP should be extension drama instead! ya da ya da ya da") - the IP and the GP. In fact, for my drama IP I made a short film, something that many people do for EE2!
And I found it manageable. Easy? No. But definitely manageable.
History extension is a big project that is true, but at the end of the day, it is only a 2500 word essay, and if you are consistently chipping away at it, it doesn't even feel like a crazy amount of work, considering you have an entire year to do it (granted you want to make sure that your topic is something your interested in as well, so you don't feel like procrastinating as much!). The class content is tricky, but again, if you stay on top of it, managable. Plus, most of the time its not really stuff you can write notes on anyway, but about forming your own opinions and arguments (I didn't write notes for any of my subjects last year, including History Extension.) - discussion and debate (and doing past papers when you can!) will serve you better in history extension than just writing notes on the readings. I studied 12 units in the HSC - would have been 13, but I dropped maths in year 11.
On another note though, do you think IPT won't get you a good mark because of scaling? Because if so, then I wouldn't take that into account! Drama is notoriously "low scaling" as a subject, however I got a raw mark of 82 and it scaled to 91, counting towards my ATAR when economics, my "highest" scaling subject didn't! Scaling doesn't matter if you do well, and you can definitely do well if you are willing to work hard, and have a passion for the subject!!