upgrade the current monitor, use the old one for the second view. Would make a great instrument or clipboard view. Dedicate more space to out of the window to increase SA.
At the rate people want to get rid of CRT monitors you can get them cheap. I just picked up two from a consignment shop. One was a 19"No Name the other a 17"sony. Nothing wrong with either of them, color still sharp. Cost was $25 each. They had about 10 more of them in the store.