I'm taking a trip to pick up a plane tomorrow and am finishing up some flight planning I JUST HAPPEN to have my Lowrance 2000C sitting on the desk next to the computer

. I am currently simulating your scenario with all the lights on as the sun is gone at the present time. With the unit forward of me at 'panel distance' and off to my right at 'arms length' (right of center in the panel...basically right in front of the passengers eyeballs) I can still 'read' all the info no problemo'. That said.....I have the 'terrain' feature and the color WILL loose some of it's brilliancy. Instead of the terrain being a rich green it will be somewhat washed out. Again....VERY readable but you loose some of the background color. With the terrain feature turned off it looks the same in front of me OR to my right in front the passenger.
That said...your location will be fine IMO....but you might consider turning it toward you a few degrees if possible.
Hope this helps!