Pretty sure the 2.1 scratchpad feature will handle both of those, yes.
Select all your 'x' and 'o' tiles using the rectangular picker as normal, and paint them into a new scratchpad. Name it 'tree' or whatever. Then use the eraser/delete like normal to remove the 'o' bits from the tiles in the scratchpad. Then you can 'select all' on the scratchpad whenever you want to paint the tree. All your scratchpads are saved between sessions.