I had the same issue, when you mount it on the floor it is tuff to read that far down. I rigged it with a ram mount to get it off the floor and to make it moveable. If you want to buy mine I just got a new boat with high gunwales and won't be using it. How does $30 sound?

Here is a link to what I have!

RAM Heavy Duty Marine Mount for Humminbird 100 300 500 700 Series Fishfinders