Thanks for the tip Joel. That reinforcing window film may just do the trick for what I'm attempting. After calling around for glass I was surprised at the quotes I was getting:
StarFire glass 3/8" thick 14"x60" safety glass is $225.00
Regular clear glass, same size $96.00
16x60 mirror (Home Depot) $22.00, along with glass cutter $8.00 and muriatic acid to remove the silvering from the mirror to make it clear glass $2.50 a gallon. Now the mirror glass is not 3/8" thick but I could use two mirrors back to back and still be half the price of the cheapest quote I got. I think I'll just stick with one though and maybe try the reinforcing film you mention.
By the way, anyone attempting to remove the silvering from a mirror with muriatic acid like I'm doing - do it in a very well ventilated area only! If in the garage, open the garage door fully! Put plastic down and put your mirror on the plastic back side up. Lay news paper or paper towel on the back of the mirror. Use a small glass jar to gently and very slowly pour the acid onto the paper. The idea here is for little or no spillage. Let the paper soak up the acid and hold it on the back of the mirror. You'll hear a sizzling, that's normal. Let old mirrors set for a half hour. New mirrors might take over an hour. Some mirrors just won't clean up well at all. Scrape off the silvering and dispose. Use rubber gloves at all times, have water handy in a bottle or by hose! Keep your nose as far from the work area as possible. Turn away to take a breath. Step outside if you feel any burning and let your nose and throat clear. Wear eye protection. Wash everything (tools, floor..etc) after use especially your hands, arms...etc This acid can be found in the pool supply area of your favorite store. Be VERY careful, it's powerful stuff.