I had a different idea after playing around and thought of a way to cache to RAM.
If you use the chunk dir as /dev/shm and than configure chunk-no-memory, you are effectively using RAM only and giving rclone a limit to use so it doesn’t break the system.
My system has 32GB so my /dev/shm is 16GB so I configured rclone to use a max chunk storage of 10GB.
rclone.conf:
chunk_total_size = 10G
My startup:
ExecStart=/usr/bin/rclone mount gmedia: /gmedia \
--allow-other \
--dir-cache-time=160h \
--cache-chunk-path /dev/shm \
--cache-chunk-no-memory \
--cache-chunk-size=10M \
--cache-info-age=168h \
--cache-workers=6 \
--cache-tmp-upload-path /data/rclone_upload \
--cache-tmp-wait-time 60m \
--buffer-size 0M \
--syslog \
--umask 002 \
--rc \
--log-level INFO
Give it a whirl!