The basic LVT-4 was unarmored, although there were armor kits available to be fitted as needed. The kit included plates for the cab, bow and side sponsons. I found some high resolution pictures of the Bovington vehicle in Flickr and if you look closely, you'll notice that the armor is flush with the mild steel plates it's fitted over.
From the pictures of US operated LVT-4s I've seen, the armor plates were also flush fitting. Spacing them would complicate plugging any penetration holes, especially on the sponsons. Remember, the armor was thin and proof only against small arms fire.