Wayne, paper negs are one of those things where its really worthwhile doing some speed testing to find a personal ei.
I know of people who rate mgiv rc at 25 and get good negs. If I tried that, I'd get a blank sheet of paper - I generally have to rate mine at about 2!
Plus remember if you are using vc, the light (colour temperature) can have an impact on speed even outdoors.
But definitely worth persevering with, I think .