I don't know, I kinda love it! I don't like sweet potatoes with marshmallows so I'd probably just put mashed potatoes on top (someone in the comments suggested piping on the mashed potatoes). But...what a cool idea! I bet it would taste pretty good too. I tend to pile my Thanksgiving plate high anyway and smother everything in gravy so it's already touching.
For some reason it made me think of that episode of friends where they are making the trifle and the pages got stuck together and she put meat in with all the fruity things. Joey liked it