'Greenhouse' is a fairly general term used a lot. I'm not an expert on them, but I do know there can be a lot of difference between one cover and another. Some 'greenhouses' are used for seedlings or plants that need part or full shade. These will have a darker/more light absorbing cover. This won't be ideal for weed (except for when it is a seedling).
Then you get some that have just plain see-through glass. That's probably too visible for you though, right?
But just to give a quick tip; there is a type of plastic like cover you can get which 'diffuses' the light. That means it can let the full spectrum and intensity through, but you can't see anything but a silhouette because it 'minces' the light right up. It looks white/frosted like. This is probably the best kind of option for a private but 'full sun' 'greenhouse'.