RAllison,
Here's the second way I attempt to level the camper. This works VERY well, but does require a little set up. I talked about this on another thread just a couple days ago, so decided to go out and get some photos this morning.
Like you, I have an Outback with the curved nose-cone. Attaching a bubble on the front of it to see out the rear window of the tow vehicle probably would not work very well. The bubble needs to be straight up and down. On the Outback, you are right, the curved front makes an awkward place to mount it.
Here's an alternative. Actually, this idea with the level on the door makes hitting that level spot pretty easy.
First, I put a piece of tape in the middle of my camper nose. I like using white electrical tape, but I didn't have any so had to use black. I want to replace this later (probably today). The Outback front cap has a center line, so it's very easy to get this straight. The center line IS center--- up and down.
The next step is to set up a "Plumb line" in the back of my truck. If you don't have a truck shell, you can do the same using your back window of the truck. I used a Command Hook and simply stuck it to the roof of the truck shell.
I then used a dow rod, Mine is square, and put a hook on the end, and simply hang it:
From the outside of the truck, it looks like this:
From the inside of the cab it look like this:
Now, all you have to do is position the camper so the dow rod and the line on the camper are exactly parallel. When they are parallel, the camper is 100% perfectly level (left to right). Unhitch, and then level front to back. I use a small stick on level on the tongue jack.
As you can see, the trailer is not 100% perfectly level. It's off just a little. To level, I'd need to add a board under drivers side.
This actually works very, very well. Easy, costs almost nothing, and works every time.