In the old days, I was often involved with setting out small (camera-sized up to maybe barrels) temporary environmental monitors of various kinds in semi-public or publicly-visible locations (with permission), such as backyards, parking lots, utility sites, and roadsides. They were often secured by being chained or strapped to convenient fixed objects, like pipes, radio towers, light poles, fences, and trees. They were not always prominently marked with ownership or other signs. They never caused any real problems or suspicion. I don't recall much of that being done in recent years (there are usually other ways to get the information now, or much more complex installations are used that are fairly obviously some kind of official setup). I'd worry, though, that the old-style stuff would be reported as a "suspicious device" and cause a panic response - at minimum, prominent markings would now be needed. How things have changed...