And some agencies have installed 100 foot telephone poles in the middle of a forrest with a small metal communications box with solar attached to house and power the repeater. Three locations I know of must have used ether a small tractor or a helicopter to install the pole as there are no roads leading to it. I found two locations while fighting a wildfire and the other one while I was hiking in the mountains.Oh, I don't know about that. Depends on the agency and what their mission is.
Definitely, federal radio systems will strive to locate at federal installations, whether their own agency's or another. Issues of paperwork. Federal agencies with rural presence will locate at whatever site is most suitable, developing new sites only if there are no other decent options. There can be federal installations on non-federal land or vice-versa. I personally am familiar with a fair number of situations where a federal radio system is located in a non-federal facility located on federal land... or vice-vice-versa.