For 50/50 access, you should pay offset CS based on your incomes adjusted yearly.
If you do that, then you have balanced all the monies in both households for normal expenses. Extraordinary expenses should be split according to income.
In my view it is simple. Normal expenses that are not directly associated with one house should be shared equally, regardless of who buys them. These should be split 50/50.
So Rep hockey, any sports, clothing, lunch programs, are all shared expenses.
The question is which are Section 7 and which are not, and how do you handle reimbursing expenses. Also keep in mind that Section 7 (non medical ones), need to be agreed to and cannot be unilaterally decided upon and expect the other person to pay.
My view is that Rep hockey is Section 7.
If the combined income of the parents is high (over 80K at least), then I think house league hockey is normal (not section 7). Or in other words CS would cover one extracurricular house league level sport or similar activity.
So for hockey to be truly fair, split Rep hockey cost according to income, but first subtract the cost of house league hockey, and share that portion 50/50. Maybe that is taking things too far, but it does make sense.
Lunch program should be split 50/50.
My kids clothing is not tied to one home and is a normal expense - so that should be split 50/50 too.
So one method is to allow both of you to keep receipts for any and all shared expenses (normal and S. 7), and balance things out monthly or so.
OR, share all Section 7, but for normal expense have a rule such as 'has to be over $100', or something and both agree you will do your best to balance the spending in normal expenses. To me this could lead to arguments ("I take the kids cloth shopping all the time"), but could work for some.