We are exploring options for a mountain top node. A question I have, is if the GPS option is supported, and if it is, can we use it to provide NTP service for the mesh?

At least one user had installed BBHN on a Rocket M2 GPS however a board.info file hasn't been provided yet to move the RM2GPS to the supported list.

The best I can say right now is to obtain one and try it.

The big question would be is how the GPS interfaces on the node. (It may be a usb to serial device inside or it may be on one of the GPIO lines ). Without somone trying it and testing it we won't really know.  The GPSD daemon may help too.

Once you can get to the gps data the NTPD daemon would let you be a time server and than you could point your other nodes to the node with GPS as the time server.