That's basically what I was asking, if that would be a posibility. I'm afraid using individual sprites for the ground might be an issue.
You talk about Rayman, that's kinda a doubt I had, because it doesn't feel like tiles at all. But something like that is what I am aiming for, a less duplicate-tile style that looks enterily the same throught the whole layout.
About the invisible solid ground that's what I do everytime, I don't like to apply behaviours to a tilemap for example, I rather have a solid invisible ground and a tile on top of it.