I don't think you can get a +2" lift from Megans. If you look at them, the shock body isn't long enough. I've played around with the ride height on my BC coilovers (same dimensions as Megans) and I don't see how they could really even go to OEM height. I've set them on close to max height and it's slightly lower than OEM. Compare a coilover at full height to an OEM spring/shock assembly and you'll see they're pretty much the same length.
And the underbody isn't really designed for off roading. Lots of stuff hangs pretty low like the cats and exhaust. My car is the opposite of what you're planning as it's as low as you can drop an FX on coilovers but the issues of ground clearance are the same. The steering rack is pretty low as well, and the tie rods are low and tiny. None of this matters on the street at a normal drive height. But I worry about it because of my drive height and the issues will be there for you as well if you ever actually go off road. Not to mention the overhangs on the FX. You'd be ok in front as the overhang isn't too long. But in the rear, you will scrape your exhaust if you go steep enough. I bang my trailer hitch leaving parking garages all the time and I've actually scraped a muffler tip once.
FWIW, my lowered BMW 335i which is lower than my FX actually clears more stuff without scraping because the overhangs are better. In addition, the underbody is enclosed and nothing hangs down. So I consistently clear speed bumps and steep garages in that car without any contact whereas in the FX, I'm pretty much guaranteed to catch something.
Long story short, I don't think you're actually going to be able to go offroad much.