Those are a few elements that you certainly have to consider. I never even climbed into an S-7, so I dont appreciate the actual real estate limitations, must be close to a Long-EZ though. But I feel your thinking is good. Good luck finding the equipment that you will be happy with.

I must admit that I have been experimenting with a few things that might interest you. I have explored the use of an iPad-mini with ForeFlight and a Stratus ll. I have been thoroughly impressed with the results. I do not intend to change my cockpit to that, but this was a very interesting experiment. I recommend that you ask around if some pilots use this combination in your neighbourhood and try to see it in flight. At least, it will give you a perspective.