I am doing this now, you can "build something" but I would just search around and try to get sat nav cubby like rocking horse poop but you cane find them then the top door will go inside.
I would suggest getting your console "dipped" speak to vlad on here, he currently has mine and is working on it for me, some great end results, main reason for doing this is because the normal console gets scuffed easily, end result after dipping is amazing.
With regards to table, most 7in will do. A few have used nexus, nooks and I am using a 7in windows ce tablet with gps, won't be putting it together till I get my console back wch won't be for a few weeks but will post pics once done. That said a number of others have lots of pics on here of the same thing