Taksan: Ocellatus has a good point.
My question to you though is, would you be able to do a DIY viewing pannel for your tank? With a little research from someone who works with fiberglass professionally, there should be a way to install a good sized viewing window, don't you agree? And it would not cost you 2k to 3k more. The cost would only be around $300.00 to $500.00 for materials at the most, I would think. The labor cost you'd be saving if you did it yourself, would be a real huge savings. Maybe you could barter goods with a person who knows how to work with fiberglass, if you do not know the in's and out's about fiberglass. I would think it would be worth a try if you're wanting to put in a viewing window.
Think about it and let us know what you decide. You've really sparked my interest now.