I am looking forward to learning from your journal! When are you planning on starting it?
WRT CL contract capacity, this is nowhere close from being a concern for me at this time ... however, given CL trades about 1/10 the volume of ES, I would suspect that 1/10 ratio applicable to contract capacity.
But then, CL average daily range varies from 140-ticks to over 300-ticks on the last 10 years, which is about 2.5 times the ES average daily range (in ticks).