I wonder if they are assuming the tablet might not have data to download mapping?
You can cache maps on wifi at home or download from a phone hotspot if doesn't have a sim card.
I think 10" tablets will be on the heavy side if they fit at all, you can probably go to about 9" and 7" feels reasonably balanced if just holding the controller.
You could have the larger tablet on a stand or something alongside with longer cable?