Preview of alpha in 3d view while UV mapping?

Hi everyone, I’m rather new to Blender so hopefully I’m asking this question correctly. Essentially I have a simple triangle that I’m UV Mapping a .png texture with transparency to, in the hopes of lining up the texture with a more complex object behind it. However, when I’m UV Mapping, all I see is a black triangle in the 3d-view, I can’t see any of the alpha transparency, and as such I can’t really match up the texture with the object behind it, is this even possible?

Basically I’m trying to create a silhouette under a large object that’s acting as the ground for a 2-d platformer game I’m working on, but I’m trying to minimize polys as much as possible, so simply extruding the ground and giving it a black material isn’t an option. Is there some better way to do this?