A number of queries here. I've got a pair of Oakley WHY 8's with Emerald Iridium Transitions lenses, which are amazingly good. 'spensive, but good. They are pretty wrap-around, which might affect the prescription. Mine isn't that strong; -1.50/-0.50. Transitions are actually ok to drive with if you don't mind the fact that they don't react in the car; the glass blocks the uv needed to cause the reaction. Cinnamon-girl, for riding in dim forest, Oakley's persimmon tint is the best compromise, but it will make things brighter when you get into sunlight again. It's fantastic for dull, misty days and winter use, tho', makes everything look like a June evening.
An alternative might be a tobacco-coloured tint. I've got an old pair of Dragon Rakes, which have three pairs of lenses - a neutral grey, a persimmon high-contrast, and one that's a sort of brown/tobacco colour. They are fantastic all-round lenses, they are dark enough that I can see happily in very bright sunlight, (like you I'm rather sensitive to bright light), but they improve contrast, and they make greens much brighter. Check out what tints are available, optitians have loads of samples, and a good one will match to a sample lens; I have some old Arnet Ravens which Brian Vousden's in Bath matched to Oakley Persimmon perfectly.