Maybe set up a trifold poster board on the table and include pictures rather than the items
Since you don't have display space behind, you could create it on the table with a trifold poster board. On the poster board, you can attach pictures of the doll furniture or even a tutorial of the dolls making the furniture. Instead of displaying the furniture itself in a diorama, display a pile of the bush honeysuckle which they can take. You could make a paper handout with instructions on how to make a simple table or chair with the honeysuckle.
If you want to do a diorama, I guess you could post signs not to touch anything (though you probably already do this). Or you could "chain" each item to the table (tie a piece of twine to each item and tape or thumbtack the other end to the table edge - kind of like how writing pens are chained to the table at the post office).