I personally don't know where the notion that schools will count CR as a 50 came from, I personally can't fathom it to be true. At the OLSAS level, CR courses are not factored into the GPA calculation.
I'm applying this year. In my first year, I took four classes in first semester and three in the second. In my final year now, I'm taking four courses each semester. I personally don't think this is going to be a big deal for me, given that I was on a full course load for all of second and third year. I likewise don't think it's gonna be a big deal for you. If you've shown that you can succeed taking a full course load for multiple years, you're through that barrier.
(btw which eco class?)