Mines a 2012 Express with no windows, no lettering, and I've put 50k on her since June. No issues with anyone, owners, managers or LEO. So I don't know about the window thing......I mean I guess I could see the issue, but I haven't had one. I don't like not having rear windows though, visibility is nice for safety sake.
Nice thing about lack of windows? Not having the sun wake you up when it comes up, no matter where it rises! Stays warmer in the back end too, not sure if thats the factory insulation or lack of windows though. (mine has the wall coverings in back with the ultra thin foam backer supposedly for noise)