I can't see the TomTom being any diffrent then my Garmin as far as mounting. With the vacuum mount if your State allows it attached to the winshield it's at eye level close enough so you can work the key board when needed. If your State does not allow winsheild mounting then a weighted soft bag sits on the dash.
What ever you do never leave the GPS setting in the open when you leave your Auto. Many have found their windows busted out and their GPSs gone. Don't even leave the mount without the GPS and clean any marks off winshield that vacuum cup leaves.
Trust me they are out looking for GPSs night and day everywhere in the world.