@Timmothias: Yes and no. The thickness is not limited, but it can not be hollow. Meaning that the roadway LOD can't be in the general shape of the house. 50x50 meters/model. And you can't have one floor, 50x50 meters, then another floor, 50x50 meters.
@NAA US Marine: Yes, there is a way around this. Breaking your model up into several pieces and assemble them in WrpEdit or the Editor.
Cheers, KTottE