I recently found on Amazon a very nice small keyboard to use with BG5ROJ digital modem. Instead of using a regular USB keyboard, this one use a RF 2.4 GHz transceiver dongle. I found this approach very convenient when using in the field. The price is really cheap… around 20$ USD. Power consumption is really low, so plenty of time to play with it! One last thing, the foot print needed in your backpack is very optimized.
73 de Jeff | VA2SS