A minimal-size integrated board with processor and RF69 radio

[bgoolsby]

I work at a research university and need to design a telemetry device to be implanted under the skin of a rodent.  I understand that 915MHz will penetrate the skin better than 2.4GHz so I've been looking at the RF69 radio.  I need the device to be as small and light as possible so I'm considering designing my own circuit board with processor (probably M0) and radio chip together.  I will need to use the RF69 chip itself rather than the module, to save space.  Has anyone already done this?  Any previous work would help me get started.  Haven't yet decided how to power it - either a tiny battery or a loop coil to pick up energy from a near-field transmitter.  Rodents predictably spend a good bit of time sleeping in a particular location so a power transmitting coil under the bedding might work.  Thanks.