I think we did it!!!!   
Finally I think we have beaten the leaks!
Here's what I posted to a fellow sufferer who posted a plea for help on the Aliner owners Blog:

We have a 2008 expedition and have had constant problems with leaks. First in the left rear corner, then the front right and next the front left. We tried every way for Sunday to find the source but simply could not. In desperation we bought a couple of rolls of Eternabond tape and taped every possible seam in the dome windows, the vents and the perimeter of the roof sections. Still leaked!!!!!   #@$^%&*E$%@!#$#%%^Y  !!!

Then took off the dome window surrounds front and rear and took a good look at the windows from the inside. There were minute cracks (stress fractures?) in the corners of each of the windows right where the leaks were. We did some research and came across a product called .....wait for this....its worth it...... you won't believe it.....Captain Tully's Creeping Crack Cure. Available from a company called Vintage Trailer Supply at about $10 + S&H for enough to do several coats on each of the 4 upper dome window corners. You can also get it from West  Marine at twice as much.The stuff really works, but you have to be prepared to put on multiple coats, let it dry in between and then be disappointed by further leaks. However, the leaks will be smaller, so you put on another three coats, and eventually the leaks stop. If you are not so fussy about how the windows look from the outside then just get some clear silicone caulk and smear that around the upper corners of each of the dome windows. These seem to be the prime offenders for leaks.

FINALLY! we are leak free!