Would love to see this take shape! The more real-world use cases and examples we can look at for inspiration the better.
It seems like many projects use a watertight box (often with a latching see-through door) with cable glands for wires. See Cases/enclosures and mounting options for some examples
The main issue I often see is the lack of a good standard mounting solution. I think if we had a good way to either mount on a pole or a wall that would be good. Also, while cable glands are workable, having a standard waterproof plug would be nice so that sensors and power could be disconnected easily rather than having them directly connected to the electronics. e.g. http://www.libelium.com/products/plug-sense/