I know there are many good but expensive products available. I am hoping to find one which is like a PNA but I can also abuse for other purposed. A tablet is just too big and not as flexible. Image a big table in the front screen of your car
By the time you've bought the hardware, bought the software and then hacked and fiddled to get the software to run on the hardware aren't you better just biting the bullet, paying a little bit more and getting a dedicated aviation product? A good GPS + the software will get close to the price of a dedicated unit and you may not get the support you need from the manufacturers. A 5" + screen seems to otherwise limit you choice.