Ok, I've tried 3 different styles of fix here. The one that works best is a combination of two.
1st try: Attached cut-to-fit foam to the housing so that it would enclose the LCD screen when the housing was closed. Didn't work so well, it allowed enough ambient light in to drown out the LCD display. The other issue is that you must be EXACT with the thickness or it will push the hatch away from the housing and unseal the O-ring.
2nd try: I attached a wide opening camera rubber eye piece to the outside of the housing over the LCD screen area. Not too bad, but if you didn't enclose the inside, you had light getting between the LCD and the eyepiece...not good.
3rd try: Reattached my foam from try 1, then attached the eyepiece to the outside of the housing. It worked quite well. The only problem is that you have to hold the camera pretty close to your eye and may lose sight of your target with your other eye.
An alternative to this is to use method 3, then add a "target" crosshair on the top of the top or side of the camera housing to accompany the eyepiece adaption. The difficulty there is that you will bounce between the two until you get used to them.