I found some neat designs here
https://www.kickstarter.com/projects/1754284174/ardurf-wireless-arduino-done-right
The all in one board is pretty impressive. Shield compatible, RFM69 radio on board, Battery Charger, boost converter to 5V when running from LiPo, wide input voltage range of 6 to 42V and all kinds of power switching circuits to keep the CPU running when different power comes and goes. The designer says 'less than $40' with everything installed, radio, serial memory et.c
Martin