Hello Brendan Merna,
From your description, you need to use the USB bootloader to downloader your application code.
Now follow me to use the KBOOT2.0 to realize it in the FRDM-K22F board.
1. Open \NXP_Kinetis_Bootloader_2_0_0\targets\MK22F51212 freedom_bootloader project
You said, you are using the KDS project, the KDS project need to modify one point.
Add this below code in bootloader_config.h
#define BL_TARGET_FLASH 1
Just like this picture:

2. Build the release version

After build, check the console, hex size, it should below 0XA000.
print size can be enabled by the following way:

3. Download the build code to your FRDM-K22F board, with USB SDA, this is the bootloader code, you must download it with debugger at first.
Then you can use the USB MSC to download your application code now.
4. find another USB cable connect the USB port in the FRDM board, J16.
You can find the FSL Loader device, this is the USB MSC interface

5. Please refer to this post to prepare the app.sb file for your application code:
USB MSD Bootloader Implementation
I have attached my modified .bin, .bd and generated .sb file.
6. Copy the k22_image.sb to the FSL Loader disc.
wait the sending finished, then power off the board, power on it again, about 5 seconds, the on board LED will blinking.
Wish it helps you!
Have a great day,
Kerry
-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------