If the picture below is your floor plan and you want to modify that TV cabinet space in the near future for bathroom storage space, you could buy some pre-finished shelving from your local big box home improvement store and create a flush backing towards the front of that cabinet. This shelving is relatively inexpensive and it can be cut to fill in the entire opening. It looks like you'll have plenty of wood trim to work with to fabricate something.
Then you you permanently install a flat screen mount of your choice in the middle of that that new surface. A simple strap over the middle of the TV would secure it for travel. If you're planning to cut a opening in your bathroom wall to make use of that cabinet space, you may want to do it prior to boarding up the front.