If it is not heavy it should be fine without the dowels. It doesn't look like it would be heavy. It will be placed at the venue, right? If it looks like it will indent the surface of the cake then use dowels. Support it in three places so it is balanced, like a tri-pod. That's what I would do, anyway. There might be some decorators out there that have used this exact topper before.
Has anyone ever used a topper like this? Does it need to be dowelled?
Is it plastic, ceramic, or something else?
I agree....if it's not heavy, don't bother. Otherwise I'd just use some drinking straws as dowels....much easier to cut than wood.
I think it's ceramic. It's certainly not as heavy as my wedding topper was - it was a precious moment's one (that was 9 years ago though, lol). If I did put dowels under it, it doesn't need a board under the fondant or something silly, does it? Do I just put three small dowels (popsicle sticks maybe) under it?
I bet that would be sufficient.