A bit late to this thread, but I had the same problem.
I have a large Yakima carrier that I sometimes put on the roof rack, and as I'm only 5'8", it's difficult to load and unload especially when we're camping.
Here's what I use:
www.xtendandclimb.com
I got the 8 1/2 foot ladder. Works great.
It's an aluminum adjustable ladder, the top yellow caps are soft plastic so it doesn't scratch the paint, it's a Type II so it holds a lot of weight, and it collapses small enough so you can easily carry it inside the Jeep.
I can use it on the left, the right, or the back. And I can get as high as I need to.
I paid $100 for it on sale at Sears.