Connect Second Monitor to Sonar

I am currently shopping for a Fish Finder, the boat I just bought has a Raymarine set-up (E80, GPS Radar and auto-pilot) Everything is pretty good, just want a second higher quality fish finder. I was looking at Dragon Fly 7, but I really want to connect a second 21" TV monitor on the fishing area and Dragonfly has NO video out option. I know there are wifi options for mobile devices, but I also want to connect Direct TV to this monitor for fishing during the game.

Can anyone suggest a fish finder with video out that is priced about the same as Dragonfly ($850 plus transducer).

Thank you.