Re-do the driveway?
That unit looks like it already has some decent ground clearance compared to the low riding models that I search out.
There are quite a few options to raise the ride height, just be aware that it WILL change the center of gravity and the handling characteristics.
Larger aka taller tires is definitely and option that can gain you a quick couple of inches. Even consider going up a wheel size.
Are the springs currently mounted on the top or bottom of the axles? If they are on the bottom of the axles you can "flip" the axles and put the springs on top, I believe etrailer.com has the necessary hardware. This is a pretty common mod with the popup crowd.