Requin, let me see if I can help.

In regards to finding your ccm/l... Just because your limit may be 40g, doesn't mean you can't eat from higher rungs. You might just eat meat one day and then try some brown rice. You'd still be under your 40 limit. And just because your ccm is 40, doesn't mean you'll never eat above that level. You may have 100 one day in maintenance and 30 the next.

Just because something is a lower rung, doesn't mean it's "free" or fail safe. For example, I can't eat melon. It gives me WICKED cravings. I can eat brown rice with zero problems. It'll kick me above my ccm, but it doesn't cause me a bump in weight, water retention, or cravings. Same with carrots or peas. You should (and in my opinion, need) to work all rungs and trial all foods you anticipate eating.

At the end of the day, you CAN go a few weeks without certain foods. Low carb is a lifetime change, so a month is a drop in the bucket. The plan is written the way it is for a reason. If you decide to do it another way, that's fine. You just may not know if it's a trial food or the nuts or the berries that is causing you a problem. Sometimes it's not the foods themselves but the way they are combined that is the issue (think fatty, salty) that drives you to overeat without even realizing it.

My personal feeling is save the experimenting until later when you have a firm grasp on what works foodwise. You might slow your losses during OWL, but it's the foundation for a successful maintenance, so I think it's the most critical phase. It took me at least 6 or 7 months to go through it, and I'm glad I did. No guessing on what I can and can't have. No guessing on what'll turn me into a craving monster. No lack of variety in my maintenance.