Does anyone know exactly how the Adjust Wall Length tool determines which products it shows as being associated?

From what I could reverse engineer, it seems that for Base and Tall cabinets, it looks for products who's height = height above floor. And for other products, it uses the productcode prompt. I'm not 100% sure if this is correct though.

The problem I'm facing is that I've created some custom products that are "floating", so the height does not equal it's height above floor. They are base cabinets though. I can get them to appear under the base/tall category by setting the heightabovefloor to it's height, but then it's out of place vertically. 

Anyone know if there's a way to get these products to show up in the Base/Tall cabinets without completely reworking the products to make height=heightabovefloor?