RFM95 LORA radio

I have a data gathering device and functioning mostly. I use two arduinos sharing an sd card. One arduino is used for data collection from various sensors and also takes a very low resolution jpg picture (about 7K) and stores it all on the sd card. When data collection is finished the sd card is electronically switched to the arduino that operates the radio to send the data. This entire part works perfectly. On the radio arduino I am using the Radiohead library. The data can be transferred successfully however due to the limitations of the radio the jpg image is a problem. Of course I can convert the small image to hex for transfer. I need to use nearly the slowest radio transfer rate inorder to get the range required. What would the proper approach to the transfer of the picture data be? Is there a better picture format to use for this purpose?