I just didn't take chances. If it doesn't come with some type of surround, I passed on the rig. Having water on wallpaper just didn't make sense to me, especially with water intrusion such a damaging problem in TTs. Even with caulk, I was concerned with it wicking past it, so I just skipped anything without some type of surround.
A lot of rigs were designed to be as cheap as possible, so anything past the "doesn't catch fire in dealer lot" stage of quality is not something one should assume.