Looks like you might want something with more floorspace; you want them to be able to regulate their own body temp, and without enough space to have a cool side and warm side, that's very difficult for them to do.
How many gallons is that tank? Is there any way for you to remove the backdrop and make it a regular non-vertical tank? BPs like floorspace more than vertical space. Once you get some more floorspace, you'll have room to put two separate hides in.